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60-397: Near the equator , the lower edge of the stratosphere is as high as 20 km (66,000 ft; 12 mi), at mid-latitudes around 10 km (33,000 ft; 6.2 mi), and at the poles about 7 km (23,000 ft; 4.3 mi). Temperatures range from an average of −51 °C (−60 °F; 220 K) near the tropopause to an average of −15 °C (5.0 °F; 260 K) near

120-485: A meridian (a great circle passing through the two poles). The IUGG standard meridian is, to the nearest millimetre, 40,007.862917 kilometres (24,859.733480 mi), one arc-minute of which is 1,852.216 metres (6,076.82 ft), explaining the SI standardization of the nautical mile as 1,852 metres (6,076 ft), more than 3 metres (9.8 ft) less than the geographical mile . The sea-level surface of Earth (the geoid )

180-434: A correct description of the source of stratospheric ozone and its ability to generate heat within the stratosphere; he also wrote that ozone may be destroyed by reacting with atomic oxygen, making two molecules of molecular oxygen. We now know that there are additional ozone loss mechanisms and that these mechanisms are catalytic, meaning that a small amount of the catalyst can destroy a great number of ozone molecules. The first

240-483: A phenomenon called Rossby-wave pumping. An interesting feature of stratospheric circulation is the quasi-biennial oscillation (QBO) in the tropical latitudes, which is driven by gravity waves that are convectively generated in the troposphere . The QBO induces a secondary circulation that is important for the global stratospheric transport of tracers, such as ozone or water vapor . Another large-scale feature that significantly influences stratospheric circulation

300-570: A timescale faster than approximately one hundred microseconds , when simple mixing of reagents is too slow and other methods of initiating reactions have to be used. The technique involves exposing a sample of material to a beam of highly accelerated electrons , where the beam is generated by a linac . It has many applications. It was developed in the late 1950s and early 1960s by John Keene in Manchester and Jack W. Boag in London. Flash photolysis

360-575: A year. Geological samples show that the Equator significantly changed positions between 48 and 12 million years ago, as sediment deposited by ocean thermal currents at the Equator shifted. The deposits by thermal currents are determined by the axis of Earth, which determines solar coverage of Earth's surface . Changes in Earth's axis can also be observed in the geographical layout of volcanic island chains, which are created by shifting hot spots under Earth's crust as

420-526: Is 8,848 m (29,029 ft). Equator The equator is a circle of latitude that divides a spheroid , such as Earth , into the Northern and Southern hemispheres . On Earth, the Equator is an imaginary line located at 0 degrees latitude , about 40,075 km (24,901 mi) in circumference, halfway between the North and South poles. The term can also be used for any other celestial body that

480-401: Is a standard for use in cartography, geodesy, and satellite navigation including GPS , also has an equatorial radius of 6,378.137 km (3,963.191 mi). For both GRS 80 and WGS 84, this results in a length for the Equator of 40,075.0167 km (24,901.4609 mi). The geographical mile is defined as one arc-minute of the Equator, so it has different values depending on which radius

540-544: Is also the equatorial radius used for the IERS 2003 ellipsoid. If it were really circular, the length of the equator would then be exactly 2π times the radius, namely 40,075.0142 km (24,901.4594 mi). The GRS 80 (Geodetic Reference System 1980) as approved and adopted by the IUGG at its Canberra, Australia meeting of 1979 has an equatorial radius of 6,378.137 km (3,963.191 mi). The WGS 84 (World Geodetic System 1984) which

600-406: Is assumed. For example, by WSG-84, the distance is 1,855.3248 metres (6,087.024 ft), while by IAU-2000, it is 1,855.3257 metres (6,087.027 ft). This is a difference of less than one millimetre (0.039 in) over the total distance (approximately 1.86 kilometres or 1.16 miles). Earth is commonly modeled as a sphere flattened 0.336% along its axis. This makes the Equator 0.16% longer than

660-400: Is caused by variations in the jet stream and other local wind shears, although areas of significant convective activity ( thunderstorms ) in the troposphere below may produce turbulence as a result of convective overshoot . On October 24, 2014, Alan Eustace became the record holder for reaching the altitude record for a manned balloon at 135,890 ft (41,419 m). Eustace also broke

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720-521: Is due to the reaction of hydroxyl radicals (•OH) with ozone. •OH is formed by the reaction of electrically excited oxygen atoms produced by ozone photolysis, with water vapor. While the stratosphere is dry, additional water vapor is produced in situ by the photochemical oxidation of methane (CH 4 ). The HO 2 radical produced by the reaction of OH with O 3 is recycled to OH by reaction with oxygen atoms or ozone. In addition, solar proton events can significantly affect ozone levels via radiolysis with

780-458: Is irregular, so the actual length of the Equator is not so easy to determine. Aviation Week and Space Technology on 9 October 1961 reported that measurements using the Transit IV-A satellite had shown the equatorial diameter from longitude 11° West to 169° East to be 1,000 feet (305 m) greater than its diameter ninety degrees away. Download coordinates as: The Equator passes through

840-472: Is produced mainly by alpha particles , which can be entirely absorbed by very thin layers of water. Summarizing, the radiolysis of water can be written as: It is believed that the enhanced concentration of hydroxyl present in irradiated water in the inner coolant loops of a light-water reactor must be taken into account when designing nuclear power plants, to prevent coolant loss resulting from corrosion . The current interest in nontraditional methods for

900-399: Is roughly spherical. In spatial (3D) geometry , as applied in astronomy , the equator of a rotating spheroid (such as a planet ) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is an imaginary line on the spheroid, equidistant from its poles , dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with

960-450: Is the dissociation of molecules by ionizing radiation . It is the cleavage of one or several chemical bonds resulting from exposure to high- energy flux . The radiation in this context is associated with ionizing radiation ; radiolysis is therefore distinguished from, for example, photolysis of the Cl 2 molecule into two Cl- radicals , where ( ultraviolet or visible spectrum ) light

1020-486: Is the breaking planetary waves resulting in intense quasi-horizontal mixing in the midlatitudes. This breaking is much more pronounced in the winter hemisphere where this region is called the surf zone. This breaking is caused due to a highly non-linear interaction between the vertically propagating planetary waves and the isolated high potential vorticity region known as the polar vortex . The resultant breaking causes large-scale mixing of air and other trace gases throughout

1080-429: Is tilted towards or away from the sun, resulting in either summer or winter in both hemispheres. This also results in a corresponding movement of the equator away from the subsolar point, which is then situated over or near the relevant tropic circle . Nevertheless, temperatures are high year-round due to the Earth's axial tilt of 23.5° not being enough to create a low minimum midday declination to sufficiently weaken

1140-623: Is used. The chemistry of concentrated solutions under ionizing radiation is extremely complex. Radiolysis can locally modify redox conditions, and therefore the speciation and the solubility of the compounds. Of all the radiation-based chemical reactions that have been studied, the most important is the decomposition of water. When exposed to radiation, water undergoes a breakdown sequence into hydrogen peroxide , hydrogen radicals , and assorted oxygen compounds, such as ozone , which when converted back into oxygen releases great amounts of energy. Some of these are explosive. This decomposition

1200-600: The UV-C region, at wavelengths shorter than about 240 nm. Radicals produced from the homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is photolysed much more rapidly than molecular oxygen as it has a stronger absorption that occurs at longer wavelengths, where the solar emission is more intense. Ozone (O 3 ) photolysis produces O and O 2 . The oxygen atom product combines with atmospheric molecular oxygen to reform O 3 , releasing heat. The rapid photolysis and reformation of ozone heat

1260-403: The plane perpendicular to its axis of rotation and midway between its geographical poles . On and near the Equator (on Earth), noontime sunlight appears almost directly overhead (no more than about 23° from the zenith ) every day, year-round. Consequently, the Equator has a rather stable daytime temperature throughout the year. On the equinoxes (approximately March 20 and September 23)

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1320-464: The subsolar point crosses Earth's equator at a shallow angle, sunlight shines perpendicular to Earth's axis of rotation, and all latitudes have nearly a 12-hour day and 12-hour night. The name is derived from medieval Latin word aequator , in the phrase circulus aequator diei et noctis , meaning 'circle equalizing day and night', from the Latin word aequare 'make equal'. The latitude of

1380-591: The Earth's equator is, by definition, 0° (zero degrees ) of arc. The equator is one of the five notable circles of latitude on Earth; the other four are the two polar circles (the Arctic Circle and the Antarctic Circle ) and the two tropical circles (the Tropic of Cancer and the Tropic of Capricorn ). The equator is the only line of latitude which is also a great circle —meaning, one whose plane passes through

1440-549: The Equator. However, its island of Annobón is 155 km (96 mi) south of the Equator, and the rest of the country lies to the north. France , Norway ( Bouvet Island ), and the United Kingdom are the other three Northern Hemisphere -based countries which have territories in the Southern Hemisphere . Seasons result from the tilt of Earth's axis away from a line perpendicular to the plane of its revolution around

1500-630: The Sun's disk contacts the horizon. Earth bulges slightly at the Equator; its average diameter is 12,742 km (7,918 mi), but the diameter at the equator is about 43 km (27 mi) greater than at the poles. Sites near the Equator, such as the Guiana Space Centre in Kourou , French Guiana , are good locations for spaceports as they have the fastest rotational speed of any latitude, 460 m (1,509 ft)/sec. The added velocity reduces

1560-513: The Sun's rays even during the solstices. High year-round temperatures extend to about 25° north or south of the equator, although the moderate seasonal temperature difference is defined by the opposing solstices (as it is at higher latitudes) near the poleward limits of this range. Near the equator, there is little temperature change throughout the year, though there may be dramatic differences in rainfall and humidity. The terms summer, autumn, winter and spring do not generally apply. Lowlands around

1620-540: The Sun. Throughout the year, the Northern and Southern hemispheres are alternately turned either toward or away from the Sun, depending on Earth's position in its orbit. The hemisphere turned toward the Sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter (see solstice ). At the equinoxes , Earth's axis is perpendicular to the Sun rather than tilted toward or away, meaning that day and night are both about 12 hours long across

1680-473: The afternoon and 23 °C (73 °F) around sunrise. Rainfall is very high away from cold ocean current upwelling zones, from 2,500 to 3,500 mm (100 to 140 in) per year. There are about 200 rainy days per year and average annual sunshine hours are around 2,000. Despite high year-round sea level temperatures, some higher altitudes such as the Andes and Mount Kilimanjaro have glaciers. The highest point on

1740-508: The airplane to stay above the turbulent weather of the troposphere. The Concorde aircraft cruised at Mach 2 at about 60,000 ft (18 km), and the SR-71 cruised at Mach 3 at 85,000 ft (26 km), all within the stratosphere. Because the temperature in the tropopause and lower stratosphere is largely constant with increasing altitude, very little convection and its resultant turbulence occurs there. Most turbulence at this altitude

1800-401: The altitudes of normal lightning and storm clouds. Upper-atmospheric lightning is believed to be electrically induced forms of luminous plasma . Lightning extending above the troposphere into the stratosphere is referred to as blue jet , and that reaching into the mesosphere as red sprite . Bacterial life survives in the stratosphere, making it a part of the biosphere . In 2001, dust

1860-452: The atoms and molecules of the cells (mainly made of water) to produce free radicals and molecules that are able to diffuse far enough to reach the critical target in the cell, the DNA , and damage it indirectly through some chemical reaction. This is the main damage mechanism for photons as they are used for example in external beam radiation therapy . Typically, the radiolytic events that lead to

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1920-520: The average daily usage (1972) of hydrogen in the U.S. of about 2 x 10^4 tons. Addition of a hydrogen-atom donor could increase this about a factor of six. It was shown that the addition of a hydrogen-atom donor such as formic acid enhances the G value for hydrogen to about 2.4 molecules per 100 eV absorbed. The same study concluded that designing such a facility would likely be too unsafe to be feasible. Gas generation by radiolytic decomposition of hydrogen-containing materials has been an area of concern for

1980-707: The axis and crust move. This is consistent with the Indian tectonic plate colliding with the Eurasian tectonic plate , which is causing the Himalayan uplift. The International Association of Geodesy (IAG) and the International Astronomical Union (IAU) use an equatorial radius of 6,378.1366 km (3,963.1903 mi) (codified as the IAU 2009 value). This equatorial radius is also in the 2003 and 2010 IERS Conventions. It

2040-460: The center of the globe. The plane of Earth's equator, when projected outwards to the celestial sphere , defines the celestial equator . In the cycle of Earth's seasons , the equatorial plane runs through the Sun twice a year : on the equinoxes in March and September . To a person on Earth, the Sun appears to travel along the equator (or along the celestial equator) at these times. Locations on

2100-483: The cold European winters of the 1960s. Stratospheric warming of the polar vortex results in its weakening. When the vortex is strong, it keeps the cold, high-pressure air masses contained in the Arctic ; when the vortex weakens, air masses move equatorward, and results in rapid changes of weather in the mid latitudes. Upper-atmospheric lightning is a family of short-lived electrical-breakdown phenomena that occur well above

2160-467: The damage of the (tumor)-cell DNA are subdivided into different stages that take place on different time scales: A suggestion has been made that in the early stages of the Earth's development when its radioactivity was almost two orders of magnitude higher than at present, radiolysis could have been the principal source of atmospheric oxygen, which ensured the conditions for the origin and development of life . Molecular hydrogen and oxidants produced by

2220-526: The discovery of an isothermal layer at around 11–14 km (6.8-8.7 mi), which is the base of the lower stratosphere. This was based on temperature profiles from mostly unmanned and a few manned instrumented balloons. The mechanism describing the formation of the ozone layer was described by British mathematician and geophysicist Sydney Chapman in 1930, and is known as the Chapman cycle or ozone–oxygen cycle . Molecular oxygen absorbs high energy sunlight in

2280-404: The equator experience the shortest sunrises and sunsets because the Sun's daily path is nearly perpendicular to the horizon for most of the year. The length of daylight (sunrise to sunset) is almost constant throughout the year; it is about 14 minutes longer than nighttime due to atmospheric refraction and the fact that sunrise begins (or sunset ends) as the upper limb, not the center, of

2340-621: The equator generally have a tropical rainforest climate , also known as an equatorial climate, though cold ocean currents cause some regions to have tropical monsoon climates with a dry season in the middle of the year, and the Somali Current generated by the Asian monsoon due to continental heating via the high Tibetan Plateau causes Greater Somalia to have an arid climate despite its equatorial location. Average annual temperatures in equatorial lowlands are around 31 °C (88 °F) during

2400-468: The equator is at the elevation of 4,690 metres (15,387 ft), at 0°0′0″N 77°59′31″W  /  0.00000°N 77.99194°W  / 0.00000; -77.99194  ( highest point on the equator ) , found on the southern slopes of Volcán Cayambe [summit 5,790 metres (18,996 ft)] in Ecuador . This is slightly above the snow line and is the only place on the equator where snow lies on

2460-502: The fuel needed to launch spacecraft eastward (in the direction of Earth's rotation) to orbit, while simultaneously avoiding costly maneuvers to flatten inclination during missions such as the Apollo Moon landings . The precise location of the Equator is not truly fixed; the true equatorial plane is perpendicular to the Earth's rotation axis , which drifts about 9 metres (30 ft) during

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2520-497: The generation of hydrogen has prompted a revisit of radiolytic splitting of water, where the interaction of various types of ionizing radiation (α, β, and γ) with water produces molecular hydrogen. This reevaluation was further prompted by the current availability of large amounts of radiation sources contained in the fuel discharged from nuclear reactors . This spent fuel is usually stored in water pools, awaiting permanent disposal or reprocessing . The yield of hydrogen resulting from

2580-677: The ground. At the equator, the snow line is around 1,000 metres (3,300 ft) lower than on Mount Everest and as much as 2,000 metres (6,600 ft) lower than the highest snow line in the world, near the Tropic of Capricorn on Llullaillaco . There is a widespread maritime tradition of holding ceremonies to mark a sailor's first crossing of the equator. In the past, these ceremonies have been notorious for their brutality, especially in naval practice. Milder line-crossing ceremonies, typically featuring King Neptune , are also held for passengers' entertainment on some civilian ocean liners and cruise ships. Radiolysis Radiolysis

2640-573: The irradiation of water with β and γ radiation is low (G-values = <1 molecule per 100 electronvolts of absorbed energy) but this is largely due to the rapid reassociation of the species arising during the initial radiolysis. If impurities are present or if physical conditions are created that prevent the establishment of a chemical equilibrium, the net production of hydrogen can be greatly enhanced. Another approach uses radioactive waste as an energy source for regeneration of spent fuel by converting sodium borate into sodium borohydride . By applying

2700-611: The land of eleven sovereign states . Indonesia is the country straddling the greatest length of the equatorial line across both land and sea. Starting at the Prime Meridian and heading eastwards, the Equator passes through: The Equator also passes through the territorial seas of three countries: Maldives (south of Gaafu Dhaalu Atoll ), Kiribati (south of Buariki Island ), and the United States (south of Baker Island ). Despite its name, no part of Equatorial Guinea lies on

2760-553: The mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere, reaching near 60 m/s (220 km/h; 130 mph) in the Southern polar vortex . In 1902, Léon Teisserenc de Bort from France and Richard Assmann from Germany, in separate but coordinated publications and following years of observations, published

2820-491: The midlatitude surf zone. The timescale of this rapid mixing is much smaller than the much slower timescales of upwelling in the tropics and downwelling in the extratropics. During northern hemispheric winters, sudden stratospheric warmings , caused by the absorption of Rossby waves in the stratosphere, can be observed in approximately half of winters when easterly winds develop in the stratosphere. These events often precede unusual winter weather and may even be responsible for

2880-438: The ozone layer allows life to exist on the surface of the planet outside of the ocean. All air entering the stratosphere must pass through the tropopause , the temperature minimum that divides the troposphere and stratosphere. The rising air is literally freeze dried; the stratosphere is a very dry place. The top of the stratosphere is called the stratopause , above which the temperature decreases with height. Sydney Chapman gave

2940-532: The proper combination of controls, stable borohydride compounds may be produced and used as hydrogen fuel storage medium. A study conducted in 1976 found an order-of-magnitude estimate can be made of the average hydrogen production rate that could be obtained by utilizing the energy liberated via radioactive decay. Based on the primary molecular hydrogen yield of 0.45 molecules/100 eV, it would be possible to obtain 10 tons per day. Hydrogen production rates in this range are not insignificant, but are small compared with

3000-580: The radiolysis of water may also provide a continuous source of energy to subsurface microbial communities (Pedersen, 1999). Such speculation is supported by a discovery in the Mponeng Gold Mine in South Africa , where the researchers found a community dominated by a new phylotype of Desulfotomaculum , feeding on primarily radiolytically produced H 2 . Pulse radiolysis is a recent method of initiating fast reactions to study reactions occurring on

3060-432: The stratosphere dynamically stable: there is no regular convection and associated turbulence in this part of the atmosphere. However, exceptionally energetic convection processes, such as volcanic eruption columns and overshooting tops in severe supercell thunderstorms , may carry convection into the stratosphere on a very local and temporary basis. Overall, the attenuation of solar UV at wavelengths that damage DNA by

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3120-438: The stratosphere in temperate latitudes. This optimizes fuel efficiency , mostly due to the low temperatures encountered near the tropopause and low air density, reducing parasitic drag on the airframe . Stated another way, it allows the airliner to fly faster while maintaining lift equal to the weight of the plane. (The fuel consumption depends on the drag, which is related to the lift by the lift-to-drag ratio .) It also allows

3180-432: The stratosphere is termed as Brewer-Dobson circulation , which is a single-celled circulation, spanning from the tropics up to the poles, consisting of the tropical upwelling of air from the tropical troposphere and the extra-tropical downwelling of air. Stratospheric circulation is a predominantly wave-driven circulation in that the tropical upwelling is induced by the wave force by the westward propagating Rossby waves , in

3240-468: The stratosphere, resulting in a temperature inversion. This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion ) ; the top of the stratosphere has a temperature of about 270 K (−3 °C or 26.6 °F ). This vertical stratification , with warmer layers above and cooler layers below, makes

3300-424: The subsequent formation of OH. Nitrous oxide (N 2 O) is produced by biological activity at the surface and is oxidised to NO in the stratosphere; the so-called NO x radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the stratosphere releasing chlorine atoms that react with ozone giving ClO and O 2 . The chlorine atoms are recycled when ClO reacts with O in

3360-408: The transport and storage of radioactive materials and waste for a number of years. Potentially combustible and corrosive gases can be generated while at the same time, chemical reactions can remove hydrogen, and these reactions can be enhanced by the presence of radiation. The balance between these competing reactions is not well known at this time. When radiation enters the body, it will interact with

3420-577: The upper stratosphere, or when ClO reacts with itself in the chemistry of the Antarctic ozone hole. Paul J. Crutzen, Mario J. Molina and F. Sherwood Rowland were awarded the Nobel Prize in Chemistry in 1995 for their work describing the formation and decomposition of stratospheric ozone. Commercial airliners typically cruise at altitudes of 9–12 km (30,000–39,000 ft) which is in the lower reaches of

3480-445: The whole of Earth. Near the equator, this means the variation in the strength of solar radiation is different relative to the time of year than it is at higher latitudes: maximum solar radiation is received during the equinoxes, when a place at the equator is under the subsolar point at high noon, and the intermediate seasons of spring and autumn occur at higher latitudes; and the minimum occurs during both solstices, when either pole

3540-455: The world records for vertical speed skydiving, reached with a peak velocity of 1,321 km/h (822 mph) and total freefall distance of 123,414 ft (37,617 m) – lasting four minutes and 27 seconds. The stratosphere is a region of intense interactions among radiative, dynamical , and chemical processes, in which the horizontal mixing of gaseous components proceeds much more rapidly than does vertical mixing. The overall circulation of

3600-542: Was collected at a height of 41 kilometres in a high-altitude balloon experiment and was found to contain bacterial material when examined later in the laboratory. Some bird species have been reported to fly at the upper levels of the troposphere. On November 29, 1973, a Rüppell's vulture ( Gyps rueppelli ) was ingested into a jet engine 11,278 m (37,000 ft) above the Ivory Coast . Bar-headed geese ( Anser indicus ) sometimes migrate over Mount Everest , whose summit

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