document_title: Earth's magnetic field

question_text: what is earth's magnetic field generated by

question_tokens: what is earth 's magnetic field generated by

text: Earth's magnetic field

text: Importance[edit]

text: The Earth's magnetic field serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation.[4] One stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds.[5] Calculations of the loss of carbon dioxide from the atmosphere of Mars, resulting from scavenging of ions by the solar wind, indicate that the dissipation of the magnetic field of Mars caused a near total loss of its atmosphere.[6][7]

text: The study of past magnetic field of the Earth is known as paleomagnetism.[8] The polarity of the Earth's magnetic field is recorded in igneous rocks, and reversals of the field are thus detectable as "stripes" centered on mid-ocean ridges where the sea floor is spreading, while the stability of the geomagnetic poles between reversals has allowed paleomagnetists to track the past motion of continents. Reversals also provide the basis for magnetostratigraphy, a way of dating rocks and sediments.[9] The field also magnetizes the crust, and magnetic anomalies can be used to search for deposits of metal ores.[10]

text: Humans have used compasses for direction finding since the 11th century A.D. and for navigation since the 12th century.[11] Although the magnetic declination does shift with time, this wandering is slow enough that a simple compass remains useful for navigation. Using magnetoreception various other organisms, ranging from some types of bacteria to pigeons, use the Earth's magnetic field for orientation and navigation.

text: Main characteristics[edit]

text: Description[edit]

text: At any location, the Earth's magnetic field can be represented by a three-dimensional vector. A typical procedure for measuring its direction is to use a compass to determine the direction of magnetic North. Its angle relative to true North is the declination (D) or variation. Facing magnetic North, the angle the field makes with the horizontal is the inclination (I) or magnetic dip. The intensity (F) of the field is proportional to the force it exerts on a magnet. Another common representation is in X (North), Y (East) and Z (Down) coordinates.[12]

text: Intensity[edit]

text: The intensity of the field is often measured in gauss (G), but is generally reported in nanoteslas (nT), with 1 G = 100,000 nT. A nanotesla is also referred to as a gamma (γ).[13]   The tesla is the SI unit of the magnetic field, B.  The Earth's field ranges between approximately 25,000 and 65,000 nT (0.25–0.65 G). By comparison, a strong refrigerator magnet has a field of about 10,000,000 nanoteslas (100 G).[14]

text: A map of intensity contours is called an isodynamic chart. As the World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs in the South Atlantic Anomaly over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.[15]

text: Inclination[edit]

text: The inclination is given by an angle that can assume values between -90° (up) to 90° (down). In the northern hemisphere, the field points downwards. It is straight down at the North Magnetic Pole and rotates upwards as the latitude decreases until it is horizontal (0°) at the magnetic equator. It continues to rotate upwards until it is straight up at the South Magnetic Pole. Inclination can be measured with a dip circle.

text: An isoclinic chart (map of inclination contours) for the Earth's magnetic field is shown below.

text: Declination[edit]

text: Declination is positive for an eastward deviation of the field relative to true north. It can be estimated by comparing the magnetic north/south heading on a compass with the direction of a celestial pole. Maps typically include information on the declination as an angle or a small diagram showing the relationship between magnetic north and true north. Information on declination for a region can be represented by a chart with isogonic lines (contour lines with each line representing a fixed declination).

text: Geographical variation[edit]

text: Components of the Earth's magnetic field at the surface from the World Magnetic Model for 2015.[15]

text:
Intensity

Inclination

Declination

text: Dipolar approximation[edit]

text: Near the surface of the Earth, its magnetic field can be closely approximated by the field of a magnetic dipole positioned at the center of the Earth and tilted at an angle of about 11° with respect to the rotational axis of the Earth.[13] The dipole is roughly equivalent to a powerful bar magnet, with its south pole pointing towards the geomagnetic North Pole.[16] This may seem surprising, but the north pole of a magnet is so defined because, if allowed to rotate freely, it points roughly northward (in the geographic sense). Since the north pole of a magnet attracts the south poles of other magnets and repels the north poles, it must be attracted to the south pole of Earth's magnet. The dipolar field accounts for 80–90% of the field in most locations.[12]

text: Magnetic poles[edit]

text: Historically, the north and south poles of a magnet were first defined by the Earth's magnetic field, not vice versa, since one of the first uses for a magnet was as a compass needle. Its North pole was defined as the pole that would be attracted by the Earth's North Magnetic Pole when the magnet was suspended so it could turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field (the place where the field is directed downward into the Earth).[17][18][19][20]

text: The positions of the magnetic poles can be defined in at least two ways: locally or globally.[21] The local definition is the point where the magnetic field is vertical.[22] This can be determined by measuring the inclination. The inclination of the Earth's field is 90° (downwards) at the North Magnetic Pole and -90° (upwards) at the South Magnetic Pole. The two poles wander independently of each other and are not directly opposite each other on the globe. They can migrate rapidly: movements of up to 40 kilometres (25 mi) per year have been observed for the North Magnetic Pole. Over the last 180 years, the North Magnetic Pole has been migrating northwestward, from Cape Adelaide in the Boothia Peninsula in 1831 to 600 kilometres (370 mi) from Resolute Bay in 2001.[23] The magnetic equator is the line where the inclination is zero (the magnetic field is horizontal).

text: The global definition of the Earth's field is based on a mathematical model. If a line is drawn through the center of the Earth, parallel to the moment of the best-fitting magnetic dipole, the two positions where it intersects the Earth's surface are called the North and South geomagnetic poles. If the Earth's magnetic field were perfectly dipolar, the geomagnetic poles and magnetic dip poles would coincide and compasses would point towards them. However, the Earth's field has a significant non-dipolar contribution, so the poles do not coincide and compasses do not generally point at either.

text: Magnetosphere[edit]

text: Earth's magnetic field, predominantly dipolar at its surface, is distorted further out by the solar wind. This is a stream of charged particles leaving the Sun's corona and accelerating to a speed of 200 to 1000 kilometres per second. They carry with them a magnetic field, the interplanetary magnetic field (IMF).[24]

text:
The solar wind exerts a pressure, and if it could reach Earth's atmosphere it would erode it. However, it is kept away by the pressure of the Earth's magnetic field. The magnetopause, the area where the pressures balance, is the boundary of the magnetosphere. Despite its name, the magnetosphere is asymmetric, with the sunward side being about 10 Earth radii out but the other side stretching out in a magnetotail that extends beyond 200 Earth radii.[25]
Sunward of the magnetopause is the bow shock, the area where the solar wind slows abruptly.[24]

text: Inside the magnetosphere is the plasmasphere, a donut-shaped region containing low-energy charged particles, or plasma. This region begins at a height of 60 km, extends up to 3 or 4 Earth radii, and includes the ionosphere. This region rotates with the Earth.[25] There are also two concentric tire-shaped regions, called the Van Allen radiation belts, with high-energy ions (energies from 0.1 to 10 million electron volts (MeV)). The inner belt is 1–2 Earth radii out while the outer belt is at 4–7 Earth radii. The plasmasphere and Van Allen belts have partial overlap, with the extent of overlap varying greatly with solar activity.[26]

text: As well as deflecting the solar wind, the Earth's magnetic field deflects cosmic rays, high-energy charged particles that are mostly from outside the Solar system. (Many cosmic rays are kept out of the Solar system by the Sun's magnetosphere, or heliosphere.[27]) By contrast, astronauts on the Moon risk exposure to radiation. Anyone who had been on the Moon's surface during a particularly violent solar eruption in 2005 would have received a lethal dose.[24]

text: Some of the charged particles do get into the magnetosphere. These spiral around field lines, bouncing back and forth between the poles several times per second. In addition, positive ions slowly drift westward and negative ions drift eastward, giving rise to a ring current. This current reduces the magnetic field at the Earth's surface.[24] Particles that penetrate the ionosphere and collide with the atoms there give rise to the lights of the aurorae and also emit X-rays.[25]

text: The varying conditions in the magnetosphere, known as space weather, are largely driven by solar activity. If the solar wind is weak, the magnetosphere expands; while if it is strong, it compresses the magnetosphere and more of it gets in. Periods of particularly intense activity, called geomagnetic storms, can occur when a coronal mass ejection erupts above the Sun and sends a shock wave through the Solar System. Such a wave can take just two days to reach the Earth. Geomagnetic storms can cause a lot of disruption; the "Halloween" storm of 2003 damaged more than a third of NASA's satellites. The largest documented storm occurred in 1859. It induced currents strong enough to short out telegraph lines, and aurorae were reported as far south as Hawaii.[24][28]

text: Time dependence[edit]

text: Short-term variations[edit]

text: The geomagnetic field changes on time scales from milliseconds to millions of years. Shorter time scales mostly arise from currents in the ionosphere (ionospheric dynamo region) and magnetosphere, and some changes can be traced to geomagnetic storms or daily variations in currents. Changes over time scales of a year or more mostly reflect changes in the Earth's interior, particularly the iron-rich core.[12]

text: Frequently, the Earth's magnetosphere is hit by solar flares causing geomagnetic storms, provoking displays of aurorae. The short-term instability of the magnetic field is measured with the K-index.[29]

text: Data from THEMIS show that the magnetic field, which interacts with the solar wind, is reduced when the magnetic orientation is aligned between Sun and Earth – opposite to the previous hypothesis. During forthcoming solar storms, this could result in blackouts and disruptions in artificial satellites.[30]

text: Secular variation[edit]

text: Changes in Earth's magnetic field on a time scale of a year or more are referred to as secular variation. Over hundreds of years, magnetic declination is observed to vary over tens of degrees.[12] A movie on the right shows how global declinations have changed over the last few centuries.[31]

text: The direction and intensity of the dipole change over time. Over the last two centuries the dipole strength has been decreasing at a rate of about 6.3% per century.[12] At this rate of decrease, the field would be negligible in about 1600 years.[32] However, this strength is about average for the last 7 thousand years, and the current rate of change is not unusual.[33]

text: A prominent feature in the non-dipolar part of the secular variation is a westward drift at a rate of about 0.2 degrees per year.[32] This drift is not the same everywhere and has varied over time. The globally averaged drift has been westward since about 1400 AD but eastward between about 1000 AD and 1400 AD.[34]

text: Changes that predate magnetic observatories are recorded in archaeological and geological materials. Such changes are referred to as paleomagnetic secular variation or paleosecular variation (PSV). The records typically include long periods of small change with occasional large changes reflecting geomagnetic excursions and reversals.[35]

text: Magnetic field reversals[edit]

text: Although generally Earth's field is approximately dipolar, with an axis that is nearly aligned with the rotational axis, occasionally the North and South geomagnetic poles trade places. Evidence for these geomagnetic reversals can be found in basalts, sediment cores taken from the ocean floors, and seafloor magnetic anomalies.[36] Reversals occur nearly randomly in time, with intervals between reversals ranging from less than 0.1 million years to as much as 50 million years. The most recent geomagnetic reversal, called the Brunhes–Matuyama reversal, occurred about 780,000 years ago.[23][37] A related phenomenon, a geomagnetic excursion, amounts to an incomplete reversal, with no change in polarity.[38][39] The Laschamp event is an example of an excursion, it having occurred during the last ice age (41,000 years ago).

text: The past magnetic field is recorded mostly by strongly magnetic minerals, particularly iron oxides such as magnetite, that can carry a permanent magnetic moment. This remanent magnetization, or remanence, can be acquired in more than one way. In lava flows, the direction of the field is "frozen" in small minerals as they cool, giving rise to a thermoremanent magnetization. In sediments, the orientation of magnetic particles acquires a slight bias towards the magnetic field as they are deposited on an ocean floor or lake bottom. This is called detrital remanent magnetization.[8]

text: Thermoremanent magnetization is the main source of the magnetic anomalies around mid-ocean ridges. As the seafloor spreads, magma wells up from the mantle, cools to form new basaltic crust on both sides of the ridge, and is carried away from it by seafloor spreading. As it cools, it records the direction of the Earth's field. When the Earth's field reverses, new basalt records the reversed direction. The result is a series of stripes that are symmetric about the ridge. A ship towing a magnetometer on the surface of the ocean can detect these stripes and infer the age of the ocean floor below. This provides information on the rate at which seafloor has spread in the past.[8]

text: Radiometric dating of lava flows has been used to establish a geomagnetic polarity time scale, part of which is shown in the image. This forms the basis of magnetostratigraphy, a geophysical correlation technique that can be used to date both sedimentary and volcanic sequences as well as the seafloor magnetic anomalies.[8]

text: Studies of lava flows on Steens Mountain, Oregon, indicate that the magnetic field could have shifted at a rate of up to 6 degrees per day at some time in Earth's history, which significantly challenges the popular understanding of how the Earth's magnetic field works.[40] This finding was later attributed to unusual rock magnetic properties of the lava flow under study, not rapid field change, by one of the original authors of the 1995 study.[41]

text: Temporary dipole tilt variations that take the dipole axis across the equator and then back to the original polarity are known as excursions.[39]

text: Earliest appearance[edit]

text: Paleomagnetic studies of Paleoarchean lava in Australia and conglomerate in South Africa have concluded that the magnetic field has been present since at least about 3,450 million years ago.[42][43][44]

text: Future[edit]

text: At present, the overall geomagnetic field is becoming weaker; the present strong deterioration corresponds to a 10–15% decline over the last 150 years and has accelerated in the past several years; geomagnetic intensity has declined almost continuously from a maximum 35% above the modern value achieved approximately 2,000 years ago. The rate of decrease and the current strength are within the normal range of variation, as shown by the record of past magnetic fields recorded in rocks.

text: The nature of Earth's magnetic field is one of heteroscedastic fluctuation. An instantaneous measurement of it, or several measurements of it across the span of decades or centuries, are not sufficient to extrapolate an overall trend in the field strength. It has gone up and down in the past for unknown reasons. Also, noting the local intensity of the dipole field (or its fluctuation) is insufficient to characterize Earth's magnetic field as a whole, as it is not strictly a dipole field. The dipole component of Earth's field can diminish even while the total magnetic field remains the same or increases.

text: The Earth's magnetic north pole is drifting from northern Canada towards Siberia with a presently accelerating rate—10 kilometres (6.2 mi) per year at the beginning of the 20th century, up to 40 kilometres (25 mi) per year in 2003,[23] and since then has only accelerated.[45]

text: Physical origin[edit]

text: The Earth's magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core.  However the process is complex, and computer models that reproduce some of its features have only been developed in the last few decades.

text: Earth's core and the geodynamo[edit]

text: The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids.[47] The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km). It is divided into a solid inner core, with a radius of 1220 km, and a liquid outer core.[48] The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about 6,000 K (5,730 °C; 10,340 °F), to the core-mantle boundary, which is about 3,800 K (3,530 °C; 6,380 °F).[49]  The heat is generated by potential energy released by heavier materials sinking toward the core (planetary differentiation, the iron catastrophe) as well as decay of radioactive elements in the interior.  The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core.[50]

text: The mechanism by which the Earth generates a magnetic field is known as a dynamo.[47] The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force).[51] These effects can be combined in a partial differential equation for the magnetic field called the magnetic induction equation,

text: where u is the velocity of the fluid; B is the magnetic B-field; and η=1/σμ is the magnetic diffusivity, which is inversely proportional to the product of the electrical conductivity σ and the permeability μ .[52]  The term ∂B/∂t is the time derivative of the field; ∇2 is the Laplace operator and ∇× is the curl operator.

text: The first term on the right hand side of the induction equation is a diffusion term. In a stationary fluid, the magnetic field declines and any concentrations of field spread out. If the Earth's dynamo shut off, the dipole part would disappear in a few tens of thousands of years.[52]

text:
In a perfect conductor (

σ
=
∞

{\displaystyle \sigma =\infty \;}

), there would be no diffusion. By Lenz's law, any change in the magnetic field would be immediately opposed by currents, so the flux through a given volume of fluid could not change. As the fluid moved, the magnetic field would go with it. The theorem describing this effect is called the frozen-in-field theorem. Even in a fluid with a finite conductivity, new field is generated by stretching field lines as the fluid moves in ways that deform it. This process could go on generating new field indefinitely, were it not that as the magnetic field increases in strength, it resists fluid motion.[52]

text: The motion of the fluid is sustained by convection, motion driven by buoyancy. The temperature increases towards the center of the Earth, and the higher temperature of the fluid lower down makes it buoyant. This buoyancy is enhanced by chemical separation: As the core cools, some of the molten iron solidifies and is plated to the inner core. In the process, lighter elements are left behind in the fluid, making it lighter. This is called compositional convection. A Coriolis effect, caused by the overall planetary rotation, tends to organize the flow into rolls aligned along the north-south polar axis.[50][52]

text: A dynamo can amplify a magnetic field, but it needs a "seed" field to get it started.[52] For the Earth, this could have been an external magnetic field. Early in its history the Sun went through a T-Tauri phase in which the solar wind would have had a magnetic field orders of magnitude larger than the present solar wind.[53] However, much of the field may have been screened out by the Earth's mantle. An alternative source is currents in the core-mantle boundary driven by chemical reactions or variations in thermal or electric conductivity. Such effects may still provide a small bias that are part of the boundary conditions for the geodynamo.[54]

text: The average magnetic field in the Earth's outer core was calculated to be 25 gausses, 50 times stronger than the field at the surface.[55]

text: Numerical models[edit]

text: Simulating the geodynamo requires numerically solving a set of nonlinear partial differential equations for the magnetohydrodynamics (MHD) of the Earth's interior. Simulation of the MHD equations is performed on a 3D grid of points and the fineness of the grid, which in part determines the realism of the solutions, is limited mainly by computer power. For decades, theorists were confined to creating kinematic dynamo computer models in which the fluid motion is chosen in advance and the effect on the magnetic field calculated. Kinematic dynamo theory was mainly a matter of trying different flow geometries and testing whether such geometries could sustain a dynamo.[56]

text: The first self-consistent dynamo models, ones that determine both the fluid motions and the magnetic field, were developed by two groups in 1995, one in Japan[57] and one in the United States.[1][58] The latter received attention because it successfully reproduced some of the characteristics of the Earth's field, including geomagnetic reversals.[56]

text: Currents in the ionosphere and magnetosphere[edit]

text: Electric currents induced in the ionosphere generate magnetic fields (ionospheric dynamo region). Such a field is always generated near where the atmosphere is closest to the Sun, causing daily alterations that can deflect surface magnetic fields by as much as one degree. Typical daily variations of field strength are about 25 nanoteslas (nT) (one part in 2000), with variations over a few seconds of typically around 1 nT (one part in 50,000).[59]

text: Measurement and analysis[edit]

text: Detection[edit]

text: The Earth's magnetic field strength was measured by Carl Friedrich Gauss in 1832[60] and has been repeatedly measured since then, showing a relative decay of about 10% over the last 150 years.[61] The Magsat satellite and later satellites have used 3-axis vector magnetometers to probe the 3-D structure of the Earth's magnetic field. The later Ørsted satellite allowed a comparison indicating a dynamic geodynamo in action that appears to be giving rise to an alternate pole under the Atlantic Ocean west of South Africa.[62]

text: Governments sometimes operate units that specialize in measurement of the Earth's magnetic field. These are geomagnetic observatories, typically part of a national Geological survey, for example the British Geological Survey's Eskdalemuir Observatory. Such observatories can measure and forecast magnetic conditions such as magnetic storms that sometimes affect communications, electric power, and other human activities.

text: The International Real-time Magnetic Observatory Network, with over 100 interlinked geomagnetic observatories around the world, has been recording the Earth's magnetic field since 1991.

text: The military determines local geomagnetic field characteristics, in order to detect anomalies in the natural background that might be caused by a significant metallic object such as a submerged submarine. Typically, these magnetic anomaly detectors are flown in aircraft like the UK's Nimrod or towed as an instrument or an array of instruments from surface ships.

text: Commercially, geophysical prospecting companies also use magnetic detectors to identify naturally occurring anomalies from ore bodies, such as the Kursk Magnetic Anomaly.

text: Crustal magnetic anomalies[edit]

text: Magnetometers detect minute deviations in the Earth's magnetic field caused by iron artifacts, kilns, some types of stone structures, and even ditches and middens in archaeological geophysics. Using magnetic instruments adapted from airborne magnetic anomaly detectors developed during World War II to detect submarines,[64] the magnetic variations across the ocean floor have been mapped. Basalt — the iron-rich, volcanic rock making up the ocean floor[65] — contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. The distortion was recognized by Icelandic mariners as early as the late 18th century.[66] More important, because the presence of magnetite gives the basalt measurable magnetic properties, these magnetic variations have provided another means to study the deep ocean floor. When newly formed rock cools, such magnetic materials record the Earth's magnetic field.[66]

text: Statistical models[edit]

text: Each measurement of the magnetic field is at a particular place and time. If an accurate estimate of the field at some other place and time is needed, the measurements must be converted to a model and the model used to make predictions.

text: Spherical harmonics[edit]

text: The most common way of analyzing the global variations in the Earth's magnetic field is to fit the measurements to a set of spherical harmonics. This was first done by Carl Friedrich Gauss.[67] Spherical harmonics are functions that oscillate over the surface of a sphere. They are the product of two functions, one that depends on latitude and one on longitude. The function of longitude is zero along zero or more great circles passing through the North and South Poles; the number of such nodal lines is the absolute value of the order m. The function of latitude is zero along zero or more latitude circles; this plus the order is equal to the degree ℓ. Each harmonic is equivalent to a particular arrangement of magnetic charges at the center of the Earth. A monopole is an isolated magnetic charge, which has never been observed. A dipole is equivalent to two opposing charges brought close together and a quadrupole to two dipoles brought together. A quadrupole field is shown in the lower figure on the right.[12]

text: Spherical harmonics can represent any scalar field (function of position) that satisfies certain properties. A magnetic field is a vector field, but if it is expressed in Cartesian components X, Y, Z, each component is the derivative of the same scalar function called the magnetic potential. Analyses of the Earth's magnetic field use a modified version of the usual spherical harmonics that differ by a multiplicative factor. A least-squares fit to the magnetic field measurements gives the Earth's field as the sum of spherical harmonics, each multiplied by the best-fitting  Gauss coefficient gmℓ or hmℓ.[12]

text: The lowest-degree Gauss coefficient, g00, gives the contribution of an isolated magnetic charge, so it is zero. The next three coefficients – g10, g11, and h11 – determine the direction and magnitude of the dipole contribution. The best fitting dipole is tilted at an angle of about 10° with respect to the rotational axis, as described earlier.[12]

text: Radial dependence[edit]

text: Spherical harmonic analysis can be used to distinguish internal from external sources if measurements are available at more than one height (for example, ground observatories and satellites). In that case, each term with coefficient gmℓ or hmℓ can be split into two terms: one that decreases with radius as 1/rℓ+1 and one that increases with radius as rℓ. The increasing terms fit the external sources (currents in the ionosphere and magnetosphere). However, averaged over a few years the external contributions average to zero.[12]

text: The remaining terms predict that the potential of a dipole source (ℓ=1) drops off as 1/r2. The magnetic field, being a derivative of the potential, drops off as 1/r3. Quadrupole terms drop off as 1/r4, and higher order terms drop off increasingly rapidly with the radius. The radius of the outer core is about half of the radius of the Earth. If the field at the core-mantle boundary is fit to spherical harmonics, the dipole part is smaller by a factor of about 8 at the surface, the quadrupole part by a factor of 16, and so on. Thus, only the components with large wavelengths can be noticeable at the surface. From a variety of arguments, it is usually assumed that only terms up to degree 14 or less have their origin in the core. These have wavelengths of about 2,000 kilometres (1,200 mi) or less. Smaller features are attributed to crustal anomalies.[12]

text: Global models[edit]

text: The International Association of Geomagnetism and Aeronomy maintains a standard global field model called the International Geomagnetic Reference Field. It is updated every five years. The 11th-generation model, IGRF11, was developed using data from satellites (Ørsted, CHAMP and SAC-C) and a world network of geomagnetic observatories.[68] The spherical harmonic expansion was truncated at degree 10, with 120 coefficients, until 2000. Subsequent models are truncated at degree 13 (195 coefficients).[69]

text: Another global field model, called the World Magnetic Model, is produced jointly by the United States National Centers for Environmental Information (formerly the National Geophysical Data Center) and the British Geological Survey. This model truncates at degree 12 (168 coefficients) with an approximate spatial resolution of 3,000 kilometers. It is the model used by the United States Department of Defense, the Ministry of Defence (United Kingdom), the United States Federal Aviation Administration (FAA), the North Atlantic Treaty Organization (NATO), and the International Hydrographic Office as well as in many civilian navigation systems.[70]

text: A third model, produced by the Goddard Space Flight Center (NASA and GSFC) and the Danish Space Research Institute, uses a "comprehensive modeling" approach that attempts to reconcile data with greatly varying temporal and spatial resolution from ground and satellite sources.[71]

text: For users with higher accuracy needs, the United States National Centers for Environmental Information developed  the Enhanced Magnetic Model (EMM), which extends to degree and order 790 and resolves magnetic anomalies down to a wavelength of 56 kilometers. It was compiled from satellite, marine, aeromagnetic and ground magnetic surveys. As of  2018[update], the latest version, EMM2017, includes data from The European Space Agency's Swarm satellite mission.[72]

text: Biomagnetism[edit]

text: Animals including birds and turtles can detect the Earth's magnetic field, and use the field to navigate during migration.[73] Some researchers have found that cows and wild deer tend to align their bodies north-south while relaxing, but not when the animals are under high-voltage power lines, suggesting that magnetism is responsible.[74][75] Other researchers reported in 2011 that they could not replicate those findings using different Google Earth images.[76]

text: Researchers found out that very weak electromagnetic fields disrupt the magnetic compass used by European robins and other songbirds to navigate using the Earth's magnetic field. Neither power lines nor cellphone signals are to blame for the electromagnetic field effect on the birds;[77] instead, the culprits have frequencies between 2 kHz and 5 MHz. These include AM radio signals and ordinary electronic equipment that might be found in businesses or private homes.[78]


document_title: List of most-viewed online videos in the first 24 hours

question_text: most viewed youtube video in 24 hours youtube

root

text: This list of most-viewed online videos in the first 24 hours contains the top 20 online videos that received the most views within 24 hours of release across the world. This list excludes trailers, which are featured on the list of most-viewed online trailers in the first 24 hours.

tag: p

text: Top videos

text:
Rank

Title

Uploader / artist1

Platform

Views (millions)2

Release date

Ref(s)

1.
"Rings" Prank
Paramount Pictures
Facebook
200.0
January 23, 2017
[1]

2.
Chewbacca Mask Lady
Candace Payne
Facebook
50.0
May 19, 2016
[2]

3.
"Idol"
BTS
YouTube
45.0
August 24, 2018
[3]

4.
"Look What You Made Me Do"
Taylor Swift
YouTube
43.2
August 27, 2017
[4][5]

5.
Massive Pillow Chair
Insider Design
Facebook
42.0
November 3, 2016
[6]

6.
YouTube Rewind: The Ultimate 2016 Challenge
YouTube Spotlight
Youtube
38.9
December 7, 2016
[7]

7.
YouTube Rewind: The Shape of 2017
YouTube Spotlight
YouTube
38.83
December 6, 2017
[8][unreliable source?]

8.
"Killshot"
Eminem
YouTube
38.1
September 14, 2018
[9]

9.
"Ddu-Du Ddu-Du"
BLACKPINK
YouTube
36.2
June 15, 2018
[10]

10.
"Gentleman"
Psy
YouTube
36.0
April 13, 2013
[5]

11.
"Fake Love"
BTS
YouTube
35.9
May 18, 2018
[5]

12.
"X (EQUIS)"
Nicky Jam (ft. J Balvin)
YouTube
29.7
March 2, 2018
[5]

12.
To Our Daughter
Kylie Jenner
YouTube
28.5
February 4, 2018
[11]

14.
Old Man Strength
Thrillist
Facebook
28.0
July 5, 2016
[12]

15.
"Hello"
Adele
Vevo
27.74
October 23, 2015
[13]

16.
YouTube Rewind: Now Watch Me 2015
YouTube Spotlight
YouTube
24.93
December 9, 2015
[14][unreliable source?]

17.
"Boom Boom"
RedOne (ft. Daddy Yankee, French Montana & Dinah Jane)
YouTube
24.1
October 27, 2017
[5]

18.
"Wrecking Ball"
Miley Cyrus
YouTube
22.65
September 9, 2013
[5]

19.
"Despacito (Remix)"
Luis Fonsi, Daddy Yankee (ft. Justin Bieber)
YouTube
22.4
April 16, 2017
[5]

20.
"DNA"
BTS
YouTube
22.3
September 18, 2017
[5]

As of 15 September 2018

tag: table

text:
^Note 1:  For music videos
^Note 2:  The number of views accumulated in the video's first 24 hours.
^Note 3:  Numbers are based on a web archive of the page after ~24 hours. Actual numbers may vary.
^Note 4:  "Hello" also reached 26.3 million views on YouTube[5]
^Note 5:  "Wrecking Ball" reached 19.3 million views on Vevo, which was a record at the time[15]


document_title: Alex Karev

question_text: where did alex karev go to medical school

text: Alex Karev

text: Storylines[edit]

text: His mother had a mental illness, and his father was often absent, as well as often becoming violent towards Alex and his mother. Alex began wrestling in high school,[5] and eventually physically confronted his father - after this, his father did not return. Alex has a younger brother, Aaron, and a younger sister, Amber; they were all placed in foster care for 5 years. Though Aaron and Amber only had a few foster families, Alex went through 17 foster families in 5 years before he reunited with his siblings. It is revealed in later seasons that Aaron was diagnosed with schizophrenia and tried to kill Amber. Alex was present when Aaron had to be committed to a psychiatric ward.

text: Alex secured a position in the surgical residency program at Seattle Grace Hospital after graduating from the University of Iowa. He initially makes a poor impression on his fellow interns meeting fellow interns Meredith Grey (Ellen Pompeo), Cristina Yang (Sandra Oh), George O'Malley (T.R. Knight), and Izzie Stevens (Katherine Heigl) whom he later taunts when he discovers she used to be a lingerie model. After initial disagreements, Alex reveals to Izzie that his father was a heroin addict who used to beat his mother. He became a wrestler so he could defend his mother, and attended university on a wrestling scholarship. He and Izzie begin a friendship. At the end of the first season, George contracts syphilis from Alex through nurse Olivia Harper, causing animosity between the two.

text: Alex asks Izzie out on a date, but he is thrown by the news that he has failed his medical board exams. Izzie is offended since he pays no attention to her during their date and so informs him that she no longer wants to go out with him. He later freezes during an emergency operation, needing George to take over from him. Alex's relationship with Izzie is damaged when he experiences erectile dysfunction with her. He goes on to sleep with Olivia again, and is caught by Izzie and they break up. After retaking his exams, Alex manages a pass, and reunites with Izzie after a bomb scare in the hospital. They break up again, however, when Izzie falls for cardiothoracic patient Denny Duquette.

text: Alex helps Izzie recover from Denny's death and advances Izzie but Izzie backs away since she is still in the process of getting over her loss and they remain friends. Alex spends a period of time working under neonatal surgeon Dr. Addison Montgomery (Kate Walsh), and though he is later released to work for plastic surgeon Dr. Mark Sloan (Eric Dane), he finds his interest returning to Addison's firm. Addison is attracted to Alex, and the two share a kiss and later sleep together. In the aftermath of a ferry accident, Alex rescues a pregnant woman (Elizabeth Reaser) who awakes with amnesia, and grows close to Alex as he helps her forging an identity for herself, picking out the name Ava. After she gives birth to her daughter, Ava's memory eventually returns, although she tries to hide it from Alex as she had recently left a bad marriage. He convinces her to tell him her true identity, and she reveals herself to be Rebecca Pope. Alex turns her down after realizing she's married, feeling that he is not good enough for her.

text: Rebecca returns and she and Alex sleep together before she goes back to her husband. Alex has a brief relationship with intern Lexie Grey (Chyler Leigh), but chooses to be with Rebecca when she returns and tells him she is pregnant. After Rebecca attempted suicide, Izzie convinces Alex to admit her for psychiatric help due to Rebecca's hallucinations of her pregnancy. Alex later breaks down in Izzie's arms, and the two kiss.

text: Later in their relationship, Izzie begins hallucinating about Denny, and uncovers the fact she has metastatic melanoma (Stage IV) with an estimated chance of 5% survival. It is revealed that Izzie's hallucinations of Denny are, in fact, caused by her tumor. Alex is shocked by the news, but finds the strength to stay by her side. Izzie plans a wedding for Meredith and Derek, but when Derek finds Izzie has another inoperable tumor in her brain, they give the wedding to Izzie and Alex, who marry in front of all their friends. Izzie debates whether or not she should undergo a risky surgery to remove her tumor and Alex supports her, but eventually insists that she should have the surgery. Alex performs CPR on Izzie after she flatlines.

text: Izzie regains a heartbeat but is soon fired leaving Alex a Dear John letter and no clue as to her whereabouts. She later returns to the hospital and says to Alex, thinking he had a hand in getting her fired, that she could not forgive him for talking to the Chief. Alex says he could not forgive her either for not giving him the benefit of the doubt and leaving without talking to him first. Alex re-kindles an old flame with Lexie. Alex seems to have recently found that his calling is actually Peds and not Plastics as he had decided in the earlier seasons. Seeing Alex's ability to handle child patients, Dr. Arizona Robbins shows an interest in mentoring him for that specialization. Alex's brother Aaron comes to Seattle Grace for surgery, and lots of painful memories resurface because of this. Meredith discovers Alex, along with Aaron and their sister Amber, had been in foster care for five years when their mother could not take care of them. Alex is also served with divorce papers from Izzie. Alex is shot in the hospital by a deceased patient's husband, but survives with the help of Lexie and Mark. While undergoing treatment, he mistakes Lexie for Izzie.

text: Following the shooting, Lexie has a mental breakdown in front of Alex and he walks away. Dr. Bailey bars Alex from surgery until he has the bullet removed, which he later allows her to do. Alex realizes that his passion lies in Pediatric Surgery. He is further shown to be excellent with children, comforting with a young patient while growing her a new trachea. He immediately gets on the wrong side of new Pediatric attending Stark while Arizona is on leave. Alex then attempts to sleep with virgin April Kepner after visiting his mom in Iowa when his brother was diagnosed schizophrenia. Alex and Meredith perform an emergent surgery on a young boy by themselves during the night shift, dealing with the angry fallout from Stark (who would not answer his pager) but gaining the wordless approval of the Chief. Alex is thrilled when Arizona returns from Africa and hopes she will come to work for the hospital again. In the meantime, Alex falls for the new OBGYN attending, Lucy Fields, and they start a relationship after she kisses him. Alex finds out about Meredith sabotaging her Alzheimer's clinical trial and rats her out in attempt to get Chief Resident.

text: The adoption counselor takes away Zola, the child Meredith wanted to adopt. Realizing his mistake, Alex apologizes to Meredith who forgives him shortly after. As the end of the fifth year of residency is near, the surgical residents, including Alex, prepare for their board exams for the different fellowships they plan on joining. Though Alex is late for his exam because he had to treat a patient, he ends up passing. Dr. Webber tells him that Johns Hopkins Hospital, which has the top program in the country, has been very impressed with him and has decided to create a position in pediatrics surgery for him and accepts the position. After finding out his decision, his current boss, Dr. Arizona Robbins, yells at him and takes his place on a plane that later crashes.

text: Following the rescue of his colleagues, Robbins' health deteriorates and amputates her leg. He extends his stay at Seattle Grace until a replacement for Robbins is found, but when he learns that the replacement will send the exchange program to UCLA, he decides not to leave. Karev buys Meredith's old house from her, and Cristina becomes his roommate. Karev forms a friendship with new intern, Jo Wilson that eventually develops into romantic feelings towards each other. Alex admits his love for Jo, and the two kiss and become a couple.

text: Alex's estranged father, Jimmy, who he hasn't seen in 18 years, is admitted to the ER as a patient. After being discharged, Jimmy plays with his band at a bar, and Alex spends several nights watching his father perform onstage. Unknowing that Alex is his son, Jimmy confides in Alex that he had another family that he hasn't seen in years. This made Alex upset and he punched Jimmy at the bar. Once returning home, Alex unleashes his hurt and anger on Jo for having encouraged him to reconnect with his father. His father returns suffering from symptoms of withdrawal and hallucinations of the past where more is revealed about Alex's childhood. Jimmy tells Alex he knows that he is his son and Alex yells at his dad stating that "I WAS THE DAD". His dad later goes into cardiac arrest and is brought into surgery, fate unknown. Alex kisses Jo at April's wedding wanting to start a family with her. That night his dad died, due to a mistake by intern, Shane Ross, and Alex is upset. He punches Ross and is later comforted by Meredith.

text: Upon the completion of his fellowship in Pediatric Surgery, Alex is given an offer to work at Dr. Oliver Lebackes' private practice office, claiming that he will have more flexible hours and "a big fat paycheck". Alex takes this offer happily. Robbins is initially angered by this decision and thinks that Alex is choosing money over substance. Eventually she realizes that he has become a wonderful surgeon and that she is happy to see him go. He later discovers that he isn't happy working at the private practice and expresses a desire to return full-time to Grey Sloan. When Cristina leaves for Switzerland, she leaves Alex her share of the board, including her seat.

text: Alex is fired by Dr. Lebackes when Maggie Pierce accidentally reveals to him that Karev was thinking about leaving the job. Webber recommended Bailey to fill Yang's board seat after she left, so Bailey and Alex fight over the chair. They both make presentations to the board and eventually Bailey wins, with a unanimous vote in her favor. He is hired back as an attending Peds surgeon and takes over full-time as Arizona pursues a fellowship with Dr. Herman. Alex continues to date Jo and his friendship with Meredith grows stronger than ever, with him taking on the role of her new person. When Derek dies and Meredith runs away, Alex is upset by her leaving without telling him where she went and calls her everyday. Eventually she calls him, tells him she is okay, and to stop calling. When she goes into labor and gives birth to Ellis Shepherd, Alex goes to see her since he is her emergency contact. He brings Meredith and her kids back to her house. She asks to move back in with him in her old house. Alex sells Meredith back the house and he and Jo rent a loft.

text: Alex and Jo continue to struggle with their relationship. Alex wants to settle down, marry Jo, and have kids. However, Jo continues to resist. When Karev proposes to her, Jo tells him she can't marry him, so he breaks up with her. Later, Alex realizes that he misses Jo and gets her back. They seem to be doing well for some time, until Alex brings up marriage again and the two fight, as Jo still continues to argue that she cannot marry him. Alex storms out, leaving their relationship uncertain. During Owen and Amelia's wedding, Alex realizes that even though she won't marry him, he loves Jo and goes back to her again. However, when he arrives at their loft, he finds Jo highly intoxicated, wearing nothing but her bra and underwear, and surgical intern, Andrew Deluca lying on top of her. Alex assumes that Deluca was attempting to take advantage of Jo while she was inebriated and is filled with rage. He beats Deluca to a pulp with his bare hands.

text: Andrew is badly injured, with his face bruised beyond recognition. He is unconscious and on the verge of dying. Alex realizes what he's done and quickly rushes Deluca to the hospital. There, the doctors call the police as they struggle to save Andrew and discover who did this to him. Alex lies to everyone and says that he found Andrew in this state and brought him to Grey Sloan. However, Ben Warren is suspicious of Karev. Meredith also quickly realizes that Alex was in fact the one who beat Deluca. She covers for him and the two continue to lie to everyone in the hospital about Alex's actions. Soon, Karev learns that Andrew wasn't doing anything wrong and that he had beaten up a good guy. Meredith decides that even though she loves Alex, she needs to turn him in. She goes to Bailey and tells her the truth. But, when the two rush to the police they find Alex being arrested for aggravated assault, as he had turned himself in. He is taken to jail and Meredith bails him out. While they wait for a trial, Bailey suspends Alex as an attending and makes him work in the clinic. Eventually, Jo finally tells Alex that the reason she couldn't marry Alex is because she is already married. Her husband is abusive and so she ran away and changed her name to Jo Wilson so that he wouldn't find her. Alex realizes that when Jo is called to the stand as a witness in the trial, this information about her past and lack of records under the name Jo Wilson may be revealed, and when the information goes public, her husband may find her. To keep her safe, he decides to take the plea deal without a trial, ensuring that he goes to jail for 2 years. However, when Alex tells Meredith this, she begs him not to and tells him that she can't lose him too because she's already lost everyone else important in her life. Alex struggles to decide whether or not to take the plea deal.

text: Meredith searches for Alex's case online, to find that the trial had been put off indefinitely. She assumes that he took the plea, and began calling and visiting various local jails to find him. After a full day of searching without finding him, she goes home to sleep, and discovers him sleeping in her bed. He explains he slept there all day. He explains that during his meeting with the D.A. Deluca came in and dropped all charges. Alex was then free to continue being Alex.

text: Development[edit]

text: Casting and creation[edit]

text: This section is empty. You can help by adding to it. (July 2012)

text: Characterization[edit]

text: This section needs expansion. You can help by adding to it. (September 2012)

text: The American Broadcasting Company (ABC) characterized Karev as "honest", "always tells it like it is", while also citing his mouth, his punctuality and him being a "smart-ass" as his weaknesses.[6] Shonda Rhimes said of Karev: "I love that we have a character who can do something wonderful but still be a selfish cranky ass about it. Alex gets to be complex in ways most characters don't because even though he’s got a moral code, his moral code is totally twisted and dark. But he's essentially good – deep down inside."[7] Carolina Paiz, one of the writers of the series, wrote: "He has so much going on inside... you think you've got him figured out but then he just reveals this whole other side to him."[8]

text: "He is superficial sleazeball who turns out to be a nice guy and a talented doctor with an amazing bedside manner, as well as the budding love interest of Katherine Heigl's character Isobel."[9] DVD Verdict wrote of the character's development in the fourth season: "Love him, hate him, or both, Karev speaks his mind, rough edges and all. But ultimately his cold heart seems to be softened by his blossoming relationship with Jane Doe/Ava/Rebecca."[10] Rhimes felt that the 100th episode during which Karev marries Stevens showed how he had grown up: "Look at him. Standing at the altar and saying those vows like a man. (...) He's become a man who can step up. And I love him for it."[11]

text: Reception[edit]

text: Analyzing Alex Karev, Rachel Simon called him "underrated;" she pointed out that Alex’s personal growth never seems to get acknowledged, as "Alex begins Grey’s as an arrogant, obnoxious intern who pushes away anyone who tries to care about him. He breaks Izzie’s heart 1,000 times, and then acts surprised when she falls for someone else. He sleeps with any girl who will have him, insults everyone who doesn’t, and generally enjoys being the hospital asshole. Yet, over the course of 10 seasons Alex has evolved, slowly and realistically, into a genuinely good person whose faults don’t miraculously disappear, but take a backseat to much better qualities."

text: Former television columnist for The Star-Ledger Alan Sepinwall disapproved of Karev's flirt with Addison as "he should take interest in a woman's speciality and respect his boss without getting in her pants."[12] Reviewing the fifth season, Chris Monfette of IGN wrote: "Alex, who'd become simply the cast's angry outcast, was uplifted as his relationship with Izzie became more and more substantial, and his bedside scenes with her toward the end were some of his character's best material yet."[13]

text: On his career path as a Pediatric Surgeon Examiner wrote, "Despite his rough exterior, Alex has a certain child-like innocence and need for acceptance. He is keen in recognizing these traits in kids, as well. He reaches out to kids on many levels." and added, "Alex has major trust issues. Maybe it was the constant beatings from his father. Or, his mother’s mental illness. Or, being shuffled through 17 foster homes over a 5 year period. Who wouldn’t have issues with a childhood like that?"


document_title: Bugatti Veyron

question_text: how many turbos does a bugatti veyron ss have

text: Bugatti Veyron

text: Origins[edit]

text: In May 1998, Volkswagen AG acquired the rights to use the Bugatti logo and the trade name Bugatti Automobiles S.A.S. To succeed the EB 110 model produced under previous ownership, the maker quickly released a series of concept cars that would culminate in the Bugatti Veyron 16.4.

text: Between October 1998 and September 1999, Bugatti introduced a series of Giugiaro-designed concept vehicles, each with permanent four-wheel drive and powered by the Volkswagen-designed W18 engine. The first, the EB118, was a 2-door coupé presented at the 1998 Paris Motor Show. The next, the EB218, was a 4-door sedan presented at the 1999 Geneva Motor Show. A third, the 18/3 Chiron, was a mid-engined sports car presented at the 1999 International Motor Show in Frankfurt.[12]

text: In October 1999, Bugatti unveiled a fourth concept car at the Tokyo Motor Show. The EB 18/4 Veyron was a mid-engined supercar styled in-house under the direction of Hartmut Warkuß.[13] In 2000 a modified version, the EB 16/4 Veyron, was displayed at motor shows in Detroit, Geneva, and Paris. Rather than the three-bank W-18 of the four previous concepts, the EB 16/4 featured the four-bank W16 engine architecture installed in every production example of the Bugatti Veyron.[14]

text: The decision to start production of the car was made by the Volkswagen Group in 2001. The first roadworthy prototype was completed in August 2003. It is identical to the later series variant except for a few details. In the transition from development to series production considerable technical problems had to be addressed, repeatedly delaying production until September 2005.[15]

text: The Veyron EB 16.4 is named in honour of Pierre Veyron, a Bugatti development engineer, test driver and company race driver who, with co-driver Jean-Pierre Wimille, won the 1939 24 hours of Le Mans while driving a Bugatti.[16] The "EB" refers to Bugatti founder Ettore Bugatti and the "16.4" refers to the engine's 16 cylinders and 4 turbochargers.[17]

text: World record controversy[edit]

text: A controversy developed in 2013 over the Veyron Super Sport's status as the world’s fastest production car, ultimately resolved in the Veyron's favour.

text: In early April 2013, driving.co.uk (also known as Sunday Times Driving) began an investigation following claims from US car maker Hennessey that its 928 kW (1,244 bhp; 1,262 PS) Hennessey Venom GT was entitled to the Guinness World Record. With a recorded speed of 427.6 km/h (265.7 mph) the Hennessey was 3.4 km/h (2.1 mph) slower than the Veyron but Hennessey dismissed Bugatti’s official record saying that the Veyron Super Sport was restricted to 415 km/h (258 mph) in production form and that for it to achieve its record top speed of 431.1 km/h (267.9 mph), the car used was in a state of tune not available to customers. Hennessey said its Venom GT was road-ready and unmodified and was therefore a production car in the strict sense of the term.[18]

text: Driving.co.uk requested clarification from Guinness World Records, which investigated this claim and found that the modification was against the official guidelines of the record. Upon finding this, Guinness World Records voided the Super Sport's record and announced it was "reviewing this category with expert external consultants to ensure our records fairly reflect achievements in this field."[19]

text: SSC North America, the producers of the Ultimate Aero TT, said that they had reclaimed the record,[20] however Guinness reinstated the Super Sport's record after coming to the conclusion that "a change to the speed limiter does not alter the fundamental design of the car or its engine."[21]

text: Hennessey later recorded the Venom GT at 435.3 km/h (270.5 mph). However, this was only in one direction. Guinness requires two runs in opposite directions to average out wind effects, so the run was not valid for a Guinness world record.[22]

text: Bugatti Veyron (2005–2011)[edit]

text: Specifications and performance[edit]

text: The Veyron features an 8.0-litre, quad-turbocharged, W16 cylinder engine, equivalent to two narrow-angle V8 engines bolted together. Each cylinder has four valves for a total of 64, but the VR8 configuration of each bank allows two overhead camshafts to drive two banks of cylinders so only four camshafts are needed. The engine is fed by four turbochargers and displaces 7,993 cubic centimetres (487.8 cu in), with a square 86 by 86 mm (3.39 by 3.39 in) bore and stroke.

text: The transmission is a dual-clutch direct-shift gearbox computer-controlled automatic with seven gear ratios, with magnesium paddles behind the steering wheel and a shift time of less than 150 milliseconds, built by Ricardo of England rather than Borg-Warner, who designed the six speed DSG used in the mainstream Volkswagen Group marques. The Veyron can be driven in either semi-automatic or fully automatic mode. A replacement transmission for the Veyron costs just over US$120,000.[23] It also has permanent all-wheel drive using the Haldex Traction system. It uses special Michelin PAX run-flat tyres, designed specifically to accommodate the Veyron's top speed, and cost US$25,000 per set.[23] The tyres can be mounted on the wheels only in France, a service which costs US$70,000.[23] Kerb weight is 1,888 kilograms (4,162 lb).[24] This gives the car a power-to-weight ratio, according to Volkswagen Group's figures, of 530 PS (390 kW; 523 bhp) per ton.

text: The car's wheelbase is 2,710 mm (106.7 in). Overall length is 4,462 mm (175.7 in) which gives 1,752.6 mm (69.0 in) of overhang. The width is 1,998 mm (78.7 in) and height 1,204 mm (47.4 in). The Bugatti Veyron has a total of ten radiators:[25]

text:
3 heat exchangers for the air-to-liquid intercoolers.
3 engine radiators.
1 for the air conditioning system.
1 transmission oil radiator.
1 differential oil radiator.
1 engine oil radiator

tag: ul

text: It has a drag coefficient of Cd=0.41 (normal condition) and Cd=0.36 (after lowering to the ground),[26] and a frontal area of 2.07 m2 (22.3 sq ft).[27] This gives it a drag area, the product of drag coefficient and frontal area, of CdA=0.74 m2 (8.0 sq ft).

text: Engine output[edit]

text: According to Volkswagen Group and certified by TÜV Süddeutschland, the final production Veyron engine produces 1,001 metric horsepower (736 kW; 987 bhp) of motive power, and generates 1,250 newton metres (922 lbf·ft) of torque.[3][28] The nominal figure has been stated by Bugatti officials to be conservative, with the real total being 1,020 metric horsepower (750 kW; 1,006 bhp) at 6,000 rpm.

text: Top speed[edit]

text: German inspection officials recorded an average top speed of the original version of 408.47 km/h (253.81 mph)[6] during test sessions on Volkswagen Group's private Ehra-Lessien test track on 19 April 2005.

text: This top speed was almost matched by James May on Top Gear in November 2006, at the Ehra-Lessien test track, at 407.5 km/h (253.2 mph)[6]. May noted that at top speed the engine consumes 45,000 litres (9,900 imp gal) of air per minute (as much as a human breathes in four days). Back in the Top Gear studio, co-presenter Jeremy Clarkson commented that most supercars felt like they were shaking apart at their top speed, and asked May if that was the case with the Veyron at 407 km/h (253 mph). May responded that the Veyron was very controlled, and only wobbled slightly when the air brake deployed.[29]

text: The car's everyday top speed is listed at 343 km/h (213 mph). When the car reaches 220 km/h (140 mph), hydraulics lower the car until it has a ground clearance of about 9 cm (3.5 in). At the same time, the wing and spoiler deploy. In this handling mode, the wing provides 3,425 newtons (770 lbf) of downforce, holding the car to the road.[25]

text: Top speed mode must be entered while the vehicle is at rest. Its driver must toggle a special top speed key to the left of their seat, which triggers a checklist to establish whether the car and its driver are ready to attempt to reach 407 km/h (253 mph). If so, the rear spoiler retracts, the front air diffusers shut, and normal 12.5 cm (4.9 in) ground clearance drops to 6.5 cm (2.6 in).

text: Braking[edit]

text: The Veyron's brakes use cross drilled, radially vented carbon fibre reinforced silicon carbide (C/SiC) composite discs, manufactured by SGL Carbon, which have a much greater resistance to brake fade when compared with conventional cast iron discs.[citation needed] The lightweight aluminium alloy monobloc brake calipers are made by AP Racing; the fronts have eight[25] titanium pistons and the rear calipers have six pistons. Bugatti claims maximum deceleration of 1.3 g on road tyres. As an added safety feature, in the event of brake failure, an anti-lock braking system (ABS) has also been installed on the handbrake.

text: Prototypes have been subjected to repeated 1.0 g braking from 312 km/h (194 mph) to 80 km/h (50 mph) without fade. With the car's acceleration from 80 km/h (50 mph) to 312 km/h (194 mph), that test can be performed every 22 seconds. At speeds above 200 km/h (120 mph), the rear wing also acts as an airbrake, snapping to a 55° angle in 0.4 seconds once brakes are applied, providing an additional 0.68 g (6.66 m/s2) of deceleration (equivalent to the stopping power of an ordinary hatchback).[25] Bugatti claims the Veyron will brake from 400 km/h (250 mph) to a standstill in less than 10 seconds, though distance covered in this time will be half a kilometre (third of a mile).[25]

text: Specifications[edit]

text:
Basic Specifications[3][4]

Layout and body style
Mid-engine, four-wheel drive, two-door coupé/targa top
Base price
€1,225,000 (GB£1,065,000/US$1,700,000)
Super Sport:
€1,912,500 (GB£1,665,000/US$2,700,000)

Internal combustion engine
8.0 litre W16, 64v 2xDOHC quad-turbocharged petrol engine
Engine displacement
and max. power
7,993 cc (487.8 cu in)
1,014.9 metric horsepower (746 kW; 1,001 bhp)
Super Sport:
1,200 metric horsepower (883 kW; 1,184 bhp)

text:
Performance

Top speed
408.47 km/h (253.81 mph) (average)
Super Sport:
431.072 km/h (267.856 mph) (average)

0–100 km/h (0.0–62.1 mph)
2.46 seconds
0–240 km/h (0.0–149.1 mph)
9.8 seconds

0–300 km/h (0.0–186.4 mph)[30]
16.7 seconds
Super Sport:
14.6 seconds[31]
0–400 km/h (0.0–248.5 mph)[32][33][not in citation given]
55 seconds

Standing quarter-mile (402 m)[34]
10.2 seconds (standard)

Braking
31.4 m (from 100 km/h to 0)

text:
Fuel economy[35]

EPA city driving
8 miles per U.S. gallon (29 L/100 km; 9.6 mpg‑imp)
EPA highway driving
14 miles per U.S. gallon (17 L/100 km; 17 mpg‑imp)

Top speed fuel economy
3 miles per U.S. gallon (78 L/100 km; 3.6 mpg‑imp), or 1.4 U.S. gal (5.3 L; 1.2 imp gal) per minute

text: Bugatti Veyron 16.4 Grand Sport (2009–2015)[edit]

text: The targa top Bugatti Veyron 16.4 Grand Sport version of the Bugatti Veyron EB 16.4 was unveiled at the 2008 Pebble Beach Concours d'Elegance.[36][37] It has extensive reinforcements to compensate for the lack of a standard roof,[38] and small changes to the windshield and running lights. Two removable tops are included, the second a temporary arrangement fashioned after an umbrella. The top speed with the hardtop in place is the same as the standard coupé version, but with the roof down is limited to 369 km/h (229 mph)—and to 130 km/h (81 mph) with the temporary soft roof. The Grand Sport edition was limited to 150 units, with the first 50 going exclusively to registered Bugatti customers. Production began in the second quarter of 2009, with the car priced at €1.4 million (excluding taxes and delivery).

text: A version was introduced at the Qatar Motor Show 2012 with a horizontal colour split with a bright yellow body framed in visible black carbon (including black-tinted wheels), seats in yellow-coloured leather upholstery with black stitching, middle console in black carbon, dashboard, steering wheel and gearshift made of black leather with yellow stitching.[39] It was priced at €1.58 million.

text: Bugatti Veyron 16.4 Super Sport, World Record Edition (2010–2011)[edit]

text: The Bugatti Veyron 16.4 Super Sport is a faster, more powerful version of the Bugatti Veyron 16.4. Production is limited to 30 units. The Super Sport has increased engine power of 1,200 PS (880 kW; 1,200 bhp), a torque of 1,500 N·m (1,100 lbf·ft), and a revised aerodynamic package.[40] The Super Sport has a 431.072 km/h (267.856 mph) top speed, making it the fastest production road car on the market[4][41][42] although it is electronically limited to 415 km/h (258 mph) to protect the tyres from disintegrating.[40]

text: The Bugatti Veyron 16.4 Super Sport World Record Edition is a version of the Bugatti Veyron 16.4 Super Sport. It is limited to five units. It has an orange body detailing, orange wheels, and a special black exposed carbon body.[43] It is not electrically limited to 415 km/h (258 mph) and will hit the record speed of 431.072 km/h (267.856 mph).

text: The vehicle was unveiled in 2010 at The Quail, followed by the 2010 Monterey Historic Races at Laguna Seca, and the 2010 Pebble Beach Concours d'Elegance.[44]

text: The Super Sport is valued at GB£1.2 million.[1][45]

text: Motorsports[edit]

text: On 4 July 2010 James May, a television presenter on BBC Two's television show Top Gear, drove the Veyron Super Sport at 417.61 km/h (259.49 mph). Later that day, Bugatti's official test driver Pierre Henri Raphanel drove the Super Sport version of the Veyron on Volkswagen's Ehra-Lessien (near Wolfsburg, Germany) high-speed test track to establish the car's top speed. With representatives of the Guinness Book of Records and German Technical Inspection Agency (TÜV) on hand, Raphanel made passes around the big oval in both directions achieving an average maximum speed of 431.072 km/h (267.856 mph), thus taking back the title from the SSC Ultimate Aero TT as the fastest production vehicle of all time.[7] The 431.072 km/h mark was reached by averaging the Super Sport's two test runs, the first reaching 427.93 km/h (265.90 mph) and the second 434.20 km/h (269.80 mph).[46]

text: On 9 April 2013 the title of "Fastest Production Car in the World" was revoked due to the deactivation of the electronic speed limiter which makes the car non stock, going against the rules of the title.[47] Later, Bugatti’s speed record was restored: "Following a thorough review conducted with a number of external experts, Guinness World Records is pleased to announce the confirmation of Bugatti’s record of Fastest production car achieved by the Veyron 16.4 Super Sport. The focus of the review was with respect to what may constitute a modification to a car’s standard specification. Having evaluated all the necessary information, Guinness World Records is now satisfied that a change to the speed limiter does not alter the fundamental design of the car or its engine."[48][49]

text: Grand Sport Vitesse (2011–2015)[edit]

text: Bugatti Veyron 16.4 Grand Sport Vitesse is a version of the Grand Sport with a Super Sport engine. It produces a maximum output of 1,200 PS (880 kW; 1,200 bhp) @ 6,400 rpm and a maximum torque of 1,500 N·m (1,100 lb·ft) @ 3,000–5,000 rpm. These figures allow the car to reach 100 km/h (62 mph) from standing in 2.6 seconds. On normal roads, the Vitesse is electronically limited to 375 km/h (233 mph).

text: The vehicle was unveiled at the 2012 Geneva Motor Show[50][51] and later appeared at the 2012 Beijing Auto Show[52] and the São Paulo Motor Show 2012.[53]

text: Base price of the Vitesse costs €1.69 million (without tax and transportation), with the 2012 Geneva Motor Show car costs €1.79 million, São Paulo Motor Show 2012 car costs €1.9 million.

text: Special editions[edit]

text: A number of special editions of the Vitesse were made. The Vitesse SE, inspired by Bugatti Type 37A, was unveiled in 2012 and sold for €1.74 million (US$2.2 million).[54][55][56] The World Record Car (WRC) Edition was limited to 8 units, debuted in 2013, and went on sale for €1.99 million.[57][58][59]

text: In 2013, Bugatti produced a series of Vitesses dedicated to racing legends, including Jean-Pierre Wimille[60][61] Jean Bugatti,[62][63] and Meo Costantini.[64] and Ettore Bugatti.[65]

text: Motorsports[edit]

text: A Bugatti Veyron 16.4 Grand Sport Vitesse driven by the Chinese racing driver Anthony Liu at Volkswagen Group's proving grounds in Ehra-Lessien became the fastest open-top production sports car, with speed of 408.84 km/h (254.04 mph). The vehicle was unveiled in Shanghai Motor Show 2013.[58]

text: After the world record attempt, Dr. Wolfgang Schreiber, President of Bugatti Automobiles S.A.S, said “When we introduced the Vitesse, we established the top speed for open-top driving to be 375 km/h. Still, we could not let go of the idea of reaching the 400 km/h mark with this car as well. The fact that we have succeeded in reaching 408.84 km/h is a thrill for me, and it reaffirms once again that Bugatti is the leader when it comes to technology in the international automotive industry." The driver, Anthony Liu, claimed "Even at such high speeds it remained incredibly comfortable and stable. With an open top, you can really experience the sound of the engine and yet even at higher speeds I did not get compromised by the wind at all.”[57]

text: Production[edit]

text: As of 6 August 2014, 405 Veyrons have been produced and delivered to customers worldwide, with orders have already been placed for another 30. Bugatti was reported to produce 300 coupes and 150 roadsters up to the end of 2015.[66]

text: Future development[edit]

text: In 2008, Bugatti then-CEO Dr Franz-Josef Paefgen confirmed that the Veyron would be replaced by another high-end model by 2012.[67] In 2011, the new CEO Wolfgang Dürheimer revealed that the company was planning to produce two models in the future — one a sports car-successor to the Veyron, the other a limousine known as the Bugatti 16C Galibier, which was later cancelled since Bugatti was later then working on a successor to the Veyron, which became the Bugatti Chiron.[68]

text: Originally the new model due in 2016 was meant to be no faster or more powerful than the Super Sport. This was later changed after a faster and more powerful in-game counterpart of the Super Sport appeared in Gran Turismo 6, known as the Bugatti Vision. The Vision debuted at the September 2015 Frankfurt Motor Show.

text: A toned-down version of the Vision concept car, now called the Chiron, was later revealed in a rumor, which was later confirmed by Bugatti itself. This version of the car is expected to be the next fastest car in the world. The Chiron debuted at the March 2016 Geneva Motor Show. Production will start in 2017 and will be limited to 500 units.

text: Last production[edit]

text: Only 450 Bugatti Veyrons were produced in a span of over 10 years. The final production vehicle, titled "LaFinale" (The End), was displayed at the Geneva Motor Show 5–15 March 2015.[69]

text: Sales[edit]

text:
Year
Units sold

2005
5[70]

2006
44[70]

2007
81[71]

2008
71[72]

2009
50[72]

2010
40[73]

2011
38[74]1

2012
31[75]

2013
47[76]

Total
407 ISI

text: ^ The last Veyron, No. 450 was sold May 2014.

tag: ol

text: Commentary[edit]

text: Top Gear[edit]

text: All three former presenters of the popular BBC motoring show Top Gear have given the Veyron considerable praise. While initially skeptical that the Veyron would ever be produced, Jeremy Clarkson later declared the Veyron "the greatest car ever made and the greatest car we will ever see in our lifetime". He also pointed out that the actual production cost of a Bugatti Veyron car was GB£5 million, but was sold to customers for just GB£1 million. When asked why, he jokingly said that Volkswagen designed the car merely as a "Technical Exercise". James May described the Veyron as "our Concorde moment." Clarkson test drove the Veyron from Alba in northern Italy to London in a race against May and Richard Hammond who made the journey in a Cessna 182 aeroplane.

text: A few episodes later, May drove the Veyron at the VW test track and took it to its top speed of 407.16 km/h (253.00 mph). In series 10, Hammond raced the Veyron against the Eurofighter Typhoon and lost. He also raced the car in Series 13 against a McLaren F1 driven by The Stig in a one-mile (1.6 km) drag race in Abu Dhabi. The commentary focused on Bugatti's "amazing technical achievement" versus the "non-gizmo" racing purity of the F1. While the F1 was quicker off the line and remained ahead until both cars were travelling at approximately 200 km/h, the Bugatti overtook its competitor from 200 to 300 km/h and emerged the victor. Hammond has stated that he did not use the Veyron's launch control in order to make the race more interesting.

text: The Veyron also won the award for "Car of the Decade" in Top Gear's end of 2010 award show. Clarkson commented "It was a car that just rewrote the rule book really, an amazing piece of engineering, a genuine Concorde moment". When the standard version was tested, it did not reach the top of the lap time leader board, with a time of 1:18.3, which was speculated as being due to the car's considerable weight disadvantage against the other cars towards the top. The Super Sport version later achieved the fastest ever time of 1:16.8 (later beaten by the Ariel Atom V8, the McLaren MP4-12C, the Pagani Huayra, the BAC Mono, the Lamborghini Aventador, McLaren 675LT and the Lamborghini Huracán),[77] as well as being taken to a verified average top speed of 431 km/h (268 mph) by Raphanel on the programme,[78] thenceforth retaking its position as the fastest production car in the world.[79][80][81]

text: Martin Roach[edit]

text: In 2011, Martin Roach's book Bugatti Veyron: A Quest for Perfection – The Story of the Greatest Car in the World[82] took the stance that the car had now become so famous that it is effectively a bona fide celebrity. The book follows its author as he attempts to track down and drive the car, along the way interviewing chief designers, test drivers, and the president of Bugatti.

text: Gordon Murray[edit]

text: Gordon Murray, designer of the McLaren F1 (which for many years was the fastest production car ever built) said the following about the Bugatti Veyron in UK auto magazine Evo during its development period:

text: The most pointless exercise on the planet has got to be this four-wheel-drive thousand-horsepower Bugatti. I think it's incredibly childish this thing people have about just one element – top speed or standing kilometre or 0–60. It's about as narrow minded as you can get as a car designer to pick on one element. It's like saying we're going to beat the original Mini because we're going to make a car 10mph faster on its top speed – but it's two foot longer and 200 kilos heavier. That's not car designing – that just reeks of a company who are paranoid...

text: Murray later brought up and criticised Volkswagen for "scamming" car buyers in the 1990s for buying the cheapest parts possible for the production of Jettas and Golfs, allowing Volkswagen to make a larger profit off their car sales, funding the construction of the Bugatti Veyron. However, Murray was impressed with the Veyron's engine and transmission after he test drove one for Road and Track magazine.[84]