1.
Tonne
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The SI symbol for the tonne is t, adopted at the same time as the unit itself in 1879. Its use is also official, for the metric ton, within the United States, having been adopted by the US National Institute of Standards and it is a symbol, not an abbreviation, and should not be followed by a period. Informal and non-approved symbols or abbreviations include T, mT, MT, in French and all English-speaking countries that are predominantly metric, tonne is the correct spelling. Before metrication in the UK the unit used for most purposes was the Imperial ton of 2,240 pounds avoirdupois, equivalent to 1,016 kg, differing by just 1. 6% from the tonne. Ton and tonne are both derived from a Germanic word in use in the North Sea area since the Middle Ages to designate a large cask. A full tun, standing about a high, could easily weigh a tonne. An English tun of wine weighs roughly a tonne,954 kg if full of water, in the United States, the unit was originally referred to using the French words millier or tonneau, but these terms are now obsolete. The Imperial and US customary units comparable to the tonne are both spelled ton in English, though they differ in mass, one tonne is equivalent to, Metric/SI,1 megagram. Equal to 1000000 grams or 1000 kilograms, megagram, Mg, is the official SI unit. Mg is distinct from mg, milligram, pounds, Exactly 1000/0. 453 592 37 lb, or approximately 2204.622622 lb. US/Short tons, Exactly 1/0. 907 184 74 short tons, or approximately 1.102311311 ST. One short ton is exactly 0.90718474 t, imperial/Long tons, Exactly 1/1. 016 046 9088 long tons, or approximately 0.9842065276 LT. One long ton is exactly 1.0160469088 t, for multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more used for the energy of nuclear explosions and other events. When used in context, there is little need to distinguish between metric and other tons, and the unit is spelt either as ton or tonne with the relevant prefix attached. *The equivalent units columns use the short scale large-number naming system used in most English-language countries. †Values in the equivalent short and long tons columns are rounded to five significant figures, ǂThough non-standard, the symbol kt is also sometimes used for knot, a unit of speed for sea-going vessels, and should not be confused with kilotonne. A metric ton unit can mean 10 kilograms within metal trading and it traditionally referred to a metric ton of ore containing 1% of metal. In the case of uranium, the acronym MTU is sometimes considered to be metric ton of uranium, in the petroleum industry the tonne of oil equivalent is a unit of energy, the amount of energy released by burning one tonne of crude oil, approximately 42 GJ
2.
Mushroom cloud
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A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of debris/smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with an explosion. They can be caused by conventional weapons, like vacuum bombs, including the ATBIP. Some volcanic eruptions and impact events can produce natural mushroom clouds, mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The stabilization altitude depends strongly on the profiles of the temperature, dew point, although the term appears to have been coined at the start of the 1950s, mushroom clouds generated by explosions were being described centuries before the atomic era. The Times published a report on 1 October 1937 of a Japanese attack on Shanghai in China which generated a great mushroom of smoke, the 1917 Halifax Explosion also produced one. During World War II, descriptions of mushroom clouds were relatively common, the atomic bomb cloud over Nagasaki, Japan was described in The Times of London of 13 August 1945 as a huge mushroom of smoke and dust. He wrote of the bomb producing a pillar of purple fire, later in 1946, the Operation Crossroads nuclear bomb tests were described as having a cauliflower cloud, but a reporter present also spoke of the mushroom, now the common symbol of the atomic age. Mushrooms have traditionally been associated both with life and death, food and poison, making them a powerful symbolic connection than, say. Mushroom clouds are formed by many sorts of large explosions under earths gravity, without gravity, the explosives by-product gases would remain spherical. Nuclear weapons are usually detonated above the ground, to maximize the effect of their spherically expanding fireball, immediately after the detonation, the fireball begins to rise into the air, acting on the same principle as a hot-air balloon. One way to analyze the motion, once the hot gas has cleared the ground sufficiently, is as a spherical cap bubble, as this gives agreement between the rate of rise and observed diameter. When the detonation altitude is low enough, these afterwinds will draw in dirt, Nuclear detonations produced high above the ground might not create mushroom clouds with a stem. Detonations underwater but near the surface produce a pillar of water, which, in collapsing, forms a cauliflower-like shape, underground detonations at low depth produce a mushroom cloud and a base surge, two different distinct clouds. The amount of radiation vented into the atmosphere decreases rapidly with increasing detonation depth, with surface and near-surface air bursts, the amount of debris lofted into the air decreases rapidly with increasing burst altitude. At burst altitudes of approximately 7 meters/kiloton^0.33, a crater is not formed, the fallout-reducing height, above which the primary radioactive particles consist mainly of the fine fireball condensation, is approximately 55 meters/kiloton^0.4. However, even at these burst altitudes, fallout may be formed by a number of mechanisms, the distribution of radiation in the mushroom cloud varies with yield of the explosion, type of weapon, fusion/fission ratio, burst altitude, terrain type, and weather. In general, lower-yield explosions have about 90% of their radioactivity in the mushroom head, in contrast, megaton-range explosions tend to have most of their radioactivity in the lower third of the mushroom cloud
3.
Fat Man
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Fat Man was the codename for the atomic bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945. It was the second of the two nuclear weapons ever used in warfare, the first being Little Boy, and its detonation marked the third-ever man-made nuclear explosion in history. It was built by scientists and engineers at Los Alamos Laboratory using plutonium from the Hanford Site, for the Fat Man mission, Bockscar was piloted by Major Charles W. Sweeney. The name Fat Man refers generically to the design of the bomb, because it had a wide. It was also known as the Mark III, Fat Man was an implosion-type nuclear weapon with a solid plutonium core. The first of type to be detonated was the Gadget, in the Trinity nuclear test, less than a month earlier on 16 July at the Alamogordo Bombing. Two more Fat Man bombs were detonated during the Operation Crossroads nuclear tests at Bikini Atoll in 1946, some 120 Fat Man units were produced between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb. The Fat Man was retired in 1950, a gun-type design was chosen, in which two sub-critical masses would be brought together by firing a bullet into a target. Tolman suggested an implosion-type nuclear weapon, but the idea attracted scant consideration, the feasibility of a plutonium bomb was questioned in 1942. Conant consulted Ernest Lawrence and Arthur Compton, who acknowledged that their scientists at Berkeley and Chicago respectively knew about the problem, the committee concluded that any problems could be overcome simply by requiring higher purity. Nonetheless, it was decided that the gun would receive the bulk of the research effort. It was assumed that the uranium gun-type bomb could be adapted from it. The gun-type and implosion-type designs were codenamed Thin Man and Fat Man respectively and these code names were created by Robert Serber, a former student of Oppenheimers who worked on the Manhattan Project. Little Boy would come last, as a variation of Thin Man and he was assisted in this work by Hugh Bradner, Charles Critchfield, and John Streib. L. T. E. Thompson was brought in as a consultant, Thompson was skeptical that an implosion could be made sufficiently symmetric. But Neddermeyers efforts in July and August at imploding tubes to produce cylinders tended to produce objects that resembled rocks, Neddermeyer was the only person who believed that implosion was practical, and only his enthusiasm kept the project alive. Oppenheimer brought John von Neumann to Los Alamos in September 1943 to take a look at implosion. The prospect of more-efficient nuclear weapons impressed Oppenheimer, Teller, and Hans Bethe, kistiakowskys name was immediately suggested, and Kistiakowsky was brought into the project as a consultant in October 1943
4.
Castle Bravo
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Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of Operation Castle. Detonated on March 1,1954, the device was the most powerful nuclear device detonated by the United States, and its first lithium-deuteride-fueled thermonuclear weapon. Castle Bravos yield was 15 megatons of TNT,2.5 times more than predicted, fallout from the detonation fell on residents of Rongelap and Utirik atolls and spread around the world. The islanders were not evacuated until three days later and suffered radiation sickness, twenty-three crewmembers of the Japanese fishing vessel Daigo Fukuryū Maru were also contaminated by fallout, experiencing acute radiation syndrome. The blast incited international reaction over atmospheric thermonuclear testing, the Bravo Crater is located at 11°41′50″N 165°16′19″E. The remains of the Castle Bravo causeway are at 11°42′6″N 165°17′7″E, the Castle Bravo device was housed in a cylinder that weighed 23,500 pounds and measured 179.5 inches in length and 53.9 inches in diameter. The primary device was a COBRA tritium-boosted atomic bomb provided by Los Alamos Scientific Laboratory and it was located at the end of the device, which, as seen in the declassified film, shows a small cone projecting from the ballistic case. This cone is the part of the parabola that was used to focus the radiation emanating from the primary to the secondary, the device was called SHRIMP and had the same basic configuration as the Ivy Mike wet device, except with a different type of fusion fuel. SHRIMP used lithium deuteride, which is solid at room temperature, Ivy Mike used cryogenic liquid deuterium, Castle Bravo was the first test by the United States of a practical deliverable fusion bomb, even though the TX-21 as proof-tested in the Bravo event was not weaponized. The successful test rendered obsolete the cryogenic design used by Ivy Mike and its derivative, the JUGHEAD. It also used a 7075 aluminium 9.5 cm thick ballistic case, the SHRIMP was at least in theory and in many aspects identical in geometry to the RUNT and RUNT II devices later proof-fired in Castle Romeo and Castle Yankee respectively. On paper it was a version of these devices, and its origins can be traced back to the spring. The United States Air Force indicated the importance of lighter weapons for delivery by the B-47 Stratojet. Los Alamos National Laboratory responded to this indication with an enriched version of the RUNT scaled down to a 3/4 scale radiation-implosion system called the SHRIMP. The proposed weight reduction would provide the Air Force with a more versatile deliverable gravity bomb. The final version tested in Castle used partially enriched lithium as its fusion fuel, natural lithium is a mixture of lithium-6 and lithium-7 isotopes. The enriched lithium used in Bravo was nominally 40% lithium-6, the fuel slugs varied in enrichment from 37 to 40% in 6Li, and the slugs with lower enrichment were positioned at the end of the fusion-fuel chamber, away from the primary. The mixture cost about 4.54 USD/g at that time, the fusion burn efficiency was ~25. 1%, the highest attained efficiency of the first TN weapon generation
5.
Gigajoule
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The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
6.
Detonation
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Detonation is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations occur in both solid and liquid explosives, as well as in reactive gases. The velocity of detonation in solid and liquid explosives is much higher than that in gaseous ones, a very wide variety of fuels may occur as gases, droplet fogs, or dust suspensions. Oxidants include halogens, ozone, hydrogen peroxide and oxides of nitrogen, gaseous detonations are often associated with a mixture of fuel and oxidant in a composition somewhat below conventional flammability ratios. They happen most often in confined systems, but they occur in large vapor clouds. Other materials, such as acetylene, ozone, and hydrogen peroxide are detonable in the absence of oxygen, processes involved in the transition between deflagration and detonation are covered thoroughly for gases by Nettleton. The simplest theory to predict the behaviour of detonations in gases is known as Chapman-Jouguet theory and this theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release. Such a theory confines the chemistry and diffusive transport processes to a thin zone. A more complex theory was advanced during World War II independently by Zeldovich, von Neumann and this theory, now known as ZND theory, admits finite-rate chemical reactions and thus describes a detonation as an infinitely thin shock wave followed by a zone of exothermic chemical reaction. With a reference frame of a shock, the following flow is subsonic, so that an acoustic reaction zone follows immediately behind the lead front. There is also evidence that the reaction zone is semi-metallic in some explosives. Both theories describe one-dimensional and steady wave fronts, indeed, such waves are quenched as their structure is destroyed. The Wood-Kirkwood detonation theory can correct for some of these limitations, experimental studies have revealed some of the conditions needed for the propagation of such fronts. The influence of increasing the concentration of diluent on expanding individual detonation cells has been elegantly demonstrated, similarly their size grows as the initial pressure falls. Since cell widths must be matched with minimum dimension of containment, mathematical modeling has steadily advanced to predicting the complex flow fields behind shocks inducing reactions. To date, none has adequately described how structure is formed and sustained behind unconfined waves, when used in explosive devices, the main cause of damage from a detonation is the supersonic blast front in the surrounding area. This is a significant distinction from deflagrations where the wave is subsonic. Therefore, detonation is most often used for explosives and the acceleration of projectiles, pulse detonation engines use the detonation wave for aerospace propulsion
7.
TNT
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Trinitrotoluene, or more specifically 2,4, 6-trinitrotoluene, is a chemical compound with the formula C6H23CH3. This yellow-colored solid is used as a reagent in chemical synthesis. The explosive yield of TNT is considered to be the measure of bombs. In chemistry, TNT is used to charge transfer salts. TNT was first prepared in 1863 by German chemist Julius Wilbrand and its potential as an explosive was not appreciated for several years, mainly because it was so difficult to detonate and because it was less powerful than alternatives. Its explosive properties were first discovered by another German chemist, Carl Häussermann, the German armed forces adopted it as a filling for artillery shells in 1902. The British started replacing lyddite with TNT in 1907, TNT is still widely used by the United States military, as well as construction companies around the world. The majority of TNT currently used by the US military is manufactured by Radford Army Ammunition Plant near Radford, in industry, TNT is produced in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mononitrotoluene, the MNT is separated and then renitrated to dinitrotoluene. In the final step, the DNT is nitrated to trinitrotoluene using a mixture of nitric acid. Nitric acid is consumed by the process, but the diluted sulfuric acid can be reconcentrated and reused. The rinse water from sulphitation is known as red water and is a significant pollutant, control of nitrogen oxides in feed nitric acid is very important because free nitrogen dioxide can result in oxidation of the methyl group of toluene. This reaction is exothermic and carries with it the risk of a runaway reaction leading to an explosion. In the laboratory,2,4, 6-trinitrotoluene is produced by a two-step process, a nitrating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, with careful cooling to maintain temperature. The nitrated toluenes are then separated, washed with dilute sodium bicarbonate to remove oxides of nitrogen, towards the end of the nitration, the mixture is heated on a steam bath. The trinitrotoluene is separated, washed with a solution of sodium sulfite. TNT is one of the most commonly used explosives for military, industrial, TNT has been used in conjunction with hydraulic fracturing, a process used to recover oil and gas from shale formations. The technique involves displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized TNT, TNT is valued partly because of its insensitivity to shock and friction, with reduced risk of accidental detonation compared to more sensitive explosives such as nitroglycerin
8.
Explosive material
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An explosive charge is a measured quantity of explosive material, which may be composed of a single ingredient or a combination of two or more. Materials that detonate are said to be high explosives and materials that deflagrate are said to be low explosives, Explosives may also be categorized by their sensitivity. Sensitive materials that can be initiated by a small amount of heat or pressure are primary explosives. A wide variety of chemicals can explode, a number are manufactured specifically for the purpose of being used as explosives. The remainder are too dangerous, sensitive, toxic, expensive, unstable, in contrast, some materials are merely combustible or flammable if they burn without exploding. The distinction, however, is not razor-sharp, though early thermal weapons, such as Greek fire, have existed since ancient times, the first widely used explosive in warfare and mining was black powder, invented in 9th century China. This material was sensitive to water, and it produced copious amounts of dark smoke, the first useful explosive stronger than black powder was nitroglycerin, developed in 1847. Since nitroglycerin is a liquid and highly unstable, it was replaced by nitrocellulose, TNT in 1863, smokeless powder, dynamite in 1867, World War I saw the adoption of TNT trinitrotoluene in artillery shells. World War II saw a use of new explosives. In turn, these have largely replaced by more powerful explosives such as C-4. However, C-4 and PETN react with metal and catch fire easily, yet unlike TNT, C-4 and PETN are waterproof, the largest commercial application of explosives is mining. In Materials Science and Engineering, explosives are used in cladding, a thin plate of some material is placed atop a thick layer of a different material, both layers typically of metal. Atop the thin layer is placed an explosive, at one end of the layer of explosive, the explosion is initiated. The two metallic layers are forced together at high speed and with great force, the explosion spreads from the initiation site throughout the explosive. Ideally, this produces a metallurgical bond between the two layers and it is possible that some fraction of the surface material from either layer eventually gets ejected when the end of material is reached. Hence, the mass of the now welded bilayer, may be less than the sum of the masses of the two initial layers, there are applications where a shock wave, and electrostatics, can result in high velocity projectiles. Thus, explosives are substances that contain an amount of energy stored in chemical bonds. Consequently, most commercial explosives are compounds containing -NO2, -ONO2 and -NHNO2 groups that
9.
Dynamite
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Dynamite is an explosive made of nitroglycerin, sorbents and stabilizers. It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht and it rapidly gained wide-scale use as a safer alternative to gun powder and nitroglycerin. Dynamite was invented by Alfred Nobel and was the first safely manageable explosive stronger than black powder, Nobel obtained patents for his invention in England on 7 May 1867, in Sweden on 19 October 1867. After its introduction, dynamite rapidly gained wide-scale use as an alternative to black powder. Nobel tightly controlled the patents, and unlicensed duplicating companies were shut down. However, a few American businessmen got around the patent by using a different formula. Nobel originally sold dynamite as Nobels Blasting Powder but decided to change the name to dynamite, from the Ancient Greek word δύναμις dýnamis, an industrialist, engineer, and inventor, Alfred Nobels father, Immanuel Nobel, built bridges and buildings in Stockholm. His construction work inspired him to new methods of blasting rock. Immanuels work with later on inspired Alfred to make explosives safer. Today dynamite is used in the mining, quarrying, construction. Dynamite is still the product of choice for trenching applications, Dynamite is occasionally used as an initiator or booster for AN and ANFO explosive charges. Nitroglycerin by itself is a strong explosive, but is extremely shock-sensitive, and degrades over time to even more unstable forms. Dynamite combines nitroglycerin with absorbents and stabilizers, rendering it safe to use, the original composition of dynamite consisted of three parts Explosive Oil, one part diatomaceous earth as the absorbent, and a small admixture of sodium carbonate antacid as the stabilizer. Diatomaceous earth is not usually used today as an absorbent medium and it has replaced by cheaper media like sawdust, wood pulp, flour. Other stabilizers like calcium carbonate or zinc oxide can be used in the place of sodium carbonate, sodium nitrate is added to the medium as an oxidizer that improves the dynamites brisance. Dynamite is usually sold in the form of cardboard cylinders about 20 cm long and about 3.2 cm in diameter, a stick of dynamite thus produced contains roughly 1 MJ of energy. Other sizes also exist, rated by either portion or by weight, Dynamite is usually rated by weight strength, usually from 20% to 60%. For example, 40% dynamite is composed of 40% nitroglycerin and 60% dope, the maximum shelf life of nitroglycerin-based dynamite is recommended as one year from the date of manufacture under good storage conditions
10.
Joule
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The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
11.
Nuclear weapon
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A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from small amounts of matter. The first test of a bomb released the same amount of energy as approximately 20,000 tons of TNT. The first thermonuclear bomb test released the same amount of energy as approximately 10 million tons of TNT, a thermonuclear weapon weighing little more than 2,400 pounds can produce an explosive force comparable to the detonation of more than 1.2 million tons of TNT. A nuclear device no larger than traditional bombs can devastate a city by blast, fire. Nuclear weapons are considered weapons of destruction, and their use. Nuclear weapons have been used twice in nuclear warfare, both times by the United States against Japan near the end of World War II, the bombings resulted in the deaths of approximately 200,000 civilians and military personnel from acute injuries sustained from the explosions. The ethics of the bombings and their role in Japans surrender remain the subject of scholarly, since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated on over two thousand occasions for the purposes of testing and demonstration. Only a few nations possess such weapons or are suspected of seeking them, israel is also believed to possess nuclear weapons, though in a policy of deliberate ambiguity, it does not acknowledge having them. Germany, Italy, Turkey, Belgium and the Netherlands are nuclear weapons sharing states, south Africa is the only country to have independently developed and then renounced and dismantled its nuclear weapons. Modernisation of weapons continues to occur, all existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is exclusively from fission reactions are commonly referred to as bombs or atom bombs. This has long noted as something of a misnomer, as their energy comes from the nucleus of the atom. The latter approach is considered more sophisticated than the former and only the approach can be used if the fissile material is plutonium. A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself. The amount of energy released by fission bombs can range from the equivalent of just under a ton to upwards of 500,000 tons of TNT, all fission reactions necessarily generate fission products, the radioactive remains of the atomic nuclei split by the fission reactions. Many fission products are highly radioactive or moderately radioactive. Fission products are the radioactive component of nuclear fallout
12.
Comprehensive Nuclear-Test-Ban Treaty
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The Comprehensive Nuclear-Test-Ban Treaty is a multilateral treaty that bans all nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nations General Assembly on 10 September 1996 but has not entered into force as eight specific states have not ratified the treaty. The movement for control of nuclear weapons began in 1945, with a call from Canada. The plan, which would serve as the basis for United States nuclear policy into the 1950s, was rejected by the Soviet Union as a US ploy to cement its nuclear dominance. Between the Trinity nuclear test of 16 July 1945 and the signing of the Partial Test Ban Treaty on 5 August 1963,499 nuclear tests were conducted. Between 1945 and 1963, the US conducted 215 atmospheric tests, the Soviet Union conducted 219, the UK conducted 21, and France conducted three. In 1954, following the Castle Bravo test, Prime Minister Jawaharlal Nehru of India issued the first appeal for an agreement on testing. Negotiations on a comprehensive test ban, primarily involved the US, UK, of primary concern throughout the negotiations, which would stretch with some interruptions to July 1963, was the system of verifying compliance with the test ban and detecting illicit tests. On the Western side, there were concerns that the Soviet Union would be able to circumvent any test ban and these fears were amplified following the US Rainier shot of 19 September 1957, which was the first contained underground test of a nuclear weapon. On the Soviet side, conversely, the on-site compliance inspections demanded by the US, disagreement over verification would lead to the Anglo-American and Soviet negotiators abandoning a comprehensive test ban in favor of a partial ban, which would be finalized on 25 July 1963. The PTBT, joined by 123 states following the three parties, banned detonations for military and civilian purposes underwater, in the atmosphere. On the one hand, enactment of the treaty was followed by a drop in the atmospheric concentration of radioactive particles. On the other hand, nuclear proliferation was not halted entirely, compared to the 499 tests from 1945 to the signing of the PTBT,436 tests were conducted over the ten years following the PTBT. Furthermore, US and Soviet underground testing continued venting radioactive gas into the atmosphere, additionally, though underground testing was generally safer than above-ground testing, underground tests continued to risk the leaking of radionuclides, including plutonium, into the ground. From 1964 through 1996, the year of the CTBTs adoption, the final non-underground test was conducted by China in 1980. The PTBT has been seen as a step towards the Nuclear Non-proliferation Treaty of 1968, under the NPT, non-nuclear weapon states were prohibited from possessing, manufacturing, and acquiring nuclear weapons or other nuclear explosive devices. All signatories, including nuclear weapon states, were committed to the goal of nuclear disarmament. In 1974, a step towards a comprehensive test ban was made with the Threshold Test Ban Treaty, ratified by the US and Soviet Union, which banned underground tests with yields above 150 kilotons
13.
Impact event
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An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have found to regularly occur in planetary systems, though the most frequent involve asteroids. Impact craters and structures are dominant landforms on many of the Solar Systems solid objects and present the strongest empirical evidence for their frequency, Impact events appear to have played a significant role in the evolution of the Solar System since its formation. Notable impact events include the Chicxulub impact,66 million years ago, throughout recorded history, hundreds of Earth impacts have been reported, with some occurrences causing deaths, injuries, property damage, or other significant localised consequences. One of the best-known recorded impacts in modern times was the Tunguska event, the Comet Shoemaker–Levy 9 impact provided the first direct observation of an extraterrestrial collision of Solar System objects, when the comet broke apart and collided with Jupiter in July 1994. Impact events have been a plot and background element in science fiction, Impact structures are the result of impact events on solid objects and, as the dominant landforms on many of the Systems solid objects, present the most solid evidence of prehistoric events. Small objects frequently collide with Earth, there is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the craters diameter. Asteroids with a 1 km diameter strike Earth every 500,000 years on average, large collisions – with 5 km objects – happen approximately once every twenty million years. The last known impact of an object of 10 km or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago, the energy released by an impactor depends on diameter, density, velocity, and angle. The diameter of most near-Earth asteroids that have not been studied by radar or infrared can generally only be estimated within about a factor of 2 based on the asteroid brightness, the density is generally assumed because the diameter and mass are also generally estimates. The minimum impact velocity on Earth is 11 km/s with asteroid impacts averaging around 17 km/s, the most probable impact angle is 45 degrees. Stony asteroids with a diameter of 4 meters enter Earths atmosphere approximately once per year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much energy as the atomic bomb dropped on Hiroshima. These ordinarily explode in the atmosphere and most or all of the solids are vaporized. However, asteroids with a diameter of 20 m, and which strike Earth approximately twice every century, the 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the one over Hiroshima. Much larger objects may impact the solid earth and create a crater, objects with a diameter less than 1 m are called meteoroids and seldom make it to the ground to become meteorites. Although no human is known to have been killed directly by an impact, in 2005 it was estimated that the chance of a single person born today dying due to an impact is around 1 in 200,000
14.
Work (thermodynamics)
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Thermodynamic work is a version of the concept of work in physics. The external factors may be electromagnetic, gravitational, or pressure/volume or other simply mechanical constraints, thermodynamic work is defined to be measurable solely from knowledge of such external macroscopic forces. These forces are associated with state variables of the system that always occur in conjugate pairs, for example pressure and volume, magnetic flux density. In the SI system of measurement, work is measured in joules, the rate at which work is performed is power. Work, i. e. weight lifted through a height, was defined in 1824 by Sadi Carnot in his famous paper Reflections on the Motive Power of Fire. Specifically, according to Carnot, We use here motive power to express the effect that a motor is capable of producing. This effect can always be likened to the elevation of a weight to a certain height and it has, as we know, as a measure, the product of the weight multiplied by the height to which it is raised. In 1845, the English physicist James Joule wrote a paper On the mechanical equivalent of heat for the British Association meeting in Cambridge. In this experiment, the friction and agitation of the paddle-wheel on the body of water caused heat to be generated which, in turn, both the temperature change ∆T of the water and the height of the fall ∆h of the weight mg were recorded. Using these values, Joule was able to determine the equivalent of heat. Joule estimated an equivalent of heat to be 819 ft•lbf/Btu. The modern day definitions of heat, work, temperature, thermodynamic work is performed by actions such as compression, and including shaft work, stirring, and rubbing. In the simplest cases, for example, there are work of change of volume against a resisting pressure, an example of isochoric work is when an outside agency, in the surrounds of the system, drives a frictional action on the surface of the system. The amount of energy transferred as work is measured through quantities defined externally to the system of interest, in an important sign convention, work that adds to the internal energy of the system is counted as positive. Nevertheless, on the hand, for historical reasons, an oft-encountered sign convention is to consider work done by the system on its surroundings as positive. Thermodynamic work does not account for any energy transferred between systems as heat or though transfer of matter, in particular, all forms of work can be converted into the mechanical work of lifting a weight, which was the original form of thermodynamic work considered by Carnot and Joule. Some authors have considered this equivalence to the lifting of a weight as a characteristic of work. In contrast, the conversion of heat into work in an engine can never exceed the Carnot efficiency
15.
Heat
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In physics, heat is the amount of energy flowing from one body to another spontaneously due to their temperature difference, or by any means other than through work or the transfer of matter. Thus, energy exchanged as heat during a process changes the energy of each body by equal. The sign of the quantity of heat can indicate the direction of the transfer, for example from system A to system B, negation indicates energy flowing in the opposite direction. While heat flows spontaneously from hot to cold, it is possible to construct a heat pump or refrigeration system that does work to increase the difference in temperature between two systems, conversely, a heat engine reduces an existing temperature difference to do work on another system. Heat is a consequence of the motion of particles. When heat is transferred between two objects or systems, the energy of the object or systems particles increases, as this occurs, the arrangement between particles becomes more and more disordered. In other words, heat is related to the concept of entropy, historically, many energy units for measurement of heat have been used. The standards-based unit in the International System of Units is the joule, Heat is measured by its effect on the states of interacting bodies, for example, by the amount of ice melted or a change in temperature. The quantification of heat via the change of a body is called calorimetry. In calorimetry, sensible heat is defined with respect to a specific chosen state variable of the system, sensible heat causes a change of the temperature of the system while leaving the chosen state variable unchanged. Heat transfer that occurs at a constant system temperature but changes the state variable is called latent heat with respect to the variable, for infinitesimal changes, the total incremental heat transfer is then the sum of the latent and sensible heat. Physicist James Clerk Maxwell, in his 1871 classic Theory of Heat, was one of many who began to build on the established idea that heat has something to do with matter in motion. This was the idea put forth by Benjamin Thompson in 1798. One of Maxwells recommended books was Heat as a Mode of Motion, Maxwell outlined four stipulations for the definition of heat, It is something which may be transferred from one body to another, according to the second law of thermodynamics. It is a quantity, and so can be treated mathematically. It cannot be treated as a substance, because it may be transformed into something that is not a material substance. Heat is one of the forms of energy and this was the way of the historical pioneers of thermodynamics. Maxwell writes that convection as such is not a purely thermal phenomenon, in thermodynamics, convection in general is regarded as transport of internal energy
16.
Kilowatt hour
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The kilowatt-hour is a derived unit of energy equal to 3.6 megajoules. If the energy is being transmitted or used at a constant rate over a period of time, the kilowatt-hour is commonly used as a billing unit for energy delivered to consumers by electric utilities. The kilowatt-hour is a unit of energy equivalent to one kilowatt of power sustained for one hour. 1 k W ⋅ h = =3600 =3600 k J =3.6 M J One watt is equal to 1 J/s. One kilowatt-hour is 3.6 megajoules, which is the amount of energy converted if work is done at a rate of one thousand watts for one hour. The base unit of energy within the International System of Units is the joule, the hour is a unit of time outside the SI, making the kilowatt-hour a non-SI unit of energy. The kilowatt-hour is not listed among the non-SI units accepted by the BIPM for use with the SI, although the hour, an electric heater rated at 1000 watts, operating for one hour uses one kilowatt-hour of energy. A television rated at 100 watts operating for 10 hours continuously uses one kilowatt-hour, a 40-watt light bulb operating continuously for 25 hours uses one kilowatt-hour. Electrical energy is sold in kilowatt-hours, cost of running equipment is the product of power in kilowatts multiplied by running time in hours, the unit price of electricity may depend upon the rate of consumption and the time of day. Industrial users may also have extra charges according to their peak usage, the symbol kWh is commonly used in commercial, educational, scientific and media publications, and is the usual practice in electrical power engineering. Other abbreviations and symbols may be encountered, kW h is less commonly used and it is consistent with SI standards. This is supported by a standard issued jointly by an international and national organization. However, at least one major usage guide and the IEEE/ASTM standard allow kWh, One guide published by NIST specifically recommends avoiding kWh to avoid possible confusion. KW·h is, like kW h, preferred with SI standards, the US official fuel-economy window sticker for electric vehicles uses the abbreviation kW-hrs. Variations in capitalization are sometimes seen, KWh, KWH, kwh, the notation kW/h, as a symbol for kilowatt-hour, is not correct. To convert a quantity measured in a unit in the column to the units in the top row, multiply by the factor in the cell where the row. All the SI prefixes are commonly applied to the watt-hour, a kilowatt-hour is 1,000 W·h (symbols kW·h, kWh or kW h, a megawatt-hour is 1 million W·h, a milliwatt-hour is 1/1000 W·h and so on. Megawatt-hours, gigawatt-hours, and terawatt-hours are often used for metering larger amounts of energy to industrial customers
17.
Kilogram
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The kilogram or kilogramme is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype of the Kilogram. The avoirdupois pound, used in both the imperial and US customary systems, is defined as exactly 0.45359237 kg, making one kilogram approximately equal to 2.2046 avoirdupois pounds. Other traditional units of weight and mass around the world are also defined in terms of the kilogram, the gram, 1/1000 of a kilogram, was provisionally defined in 1795 as the mass of one cubic centimeter of water at the melting point of ice. The final kilogram, manufactured as a prototype in 1799 and from which the IPK was derived in 1875, had an equal to the mass of 1 dm3 of water at its maximum density. The kilogram is the only SI base unit with an SI prefix as part of its name and it is also the only SI unit that is still directly defined by an artifact rather than a fundamental physical property that can be reproduced in different laboratories. Three other base units and 17 derived units in the SI system are defined relative to the kilogram, only 8 other units do not require the kilogram in their definition, temperature, time and frequency, length, and angle. At its 2011 meeting, the CGPM agreed in principle that the kilogram should be redefined in terms of the Planck constant, the decision was originally deferred until 2014, in 2014 it was deferred again until the next meeting. There are currently several different proposals for the redefinition, these are described in the Proposed Future Definitions section below, the International Prototype Kilogram is rarely used or handled. In the decree of 1795, the term gramme thus replaced gravet, the French spelling was adopted in the United Kingdom when the word was used for the first time in English in 1797, with the spelling kilogram being adopted in the United States. In the United Kingdom both spellings are used, with kilogram having become by far the more common, UK law regulating the units to be used when trading by weight or measure does not prevent the use of either spelling. In the 19th century the French word kilo, a shortening of kilogramme, was imported into the English language where it has used to mean both kilogram and kilometer. In 1935 this was adopted by the IEC as the Giorgi system, now known as MKS system. In 1948 the CGPM commissioned the CIPM to make recommendations for a practical system of units of measurement. This led to the launch of SI in 1960 and the subsequent publication of the SI Brochure, the kilogram is a unit of mass, a property which corresponds to the common perception of how heavy an object is. Mass is a property, that is, it is related to the tendency of an object at rest to remain at rest, or if in motion to remain in motion at a constant velocity. Accordingly, for astronauts in microgravity, no effort is required to hold objects off the cabin floor, they are weightless. However, since objects in microgravity still retain their mass and inertia, the ratio of the force of gravity on the two objects, measured by the scale, is equal to the ratio of their masses. On April 7,1795, the gram was decreed in France to be the weight of a volume of pure water equal to the cube of the hundredth part of the metre
18.
Celsius
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Celsius, also known as centigrade, is a metric scale and unit of measurement for temperature. As an SI derived unit, it is used by most countries in the world and it is named after the Swedish astronomer Anders Celsius, who developed a similar temperature scale. The degree Celsius can refer to a temperature on the Celsius scale as well as a unit to indicate a temperature interval. Before being renamed to honour Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps. The scale is based on 0° for the point of water. This scale is widely taught in schools today, by international agreement the unit degree Celsius and the Celsius scale are currently defined by two different temperatures, absolute zero, and the triple point of VSMOW. This definition also precisely relates the Celsius scale to the Kelvin scale, absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C. The temperature of the point of water is defined as precisely 273.16 K at 611.657 pascals pressure. This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in 273.16 of the difference between absolute zero and the point of water. Thus, it sets the magnitude of one degree Celsius and that of one kelvin as exactly the same, additionally, it establishes the difference between the two scales null points as being precisely 273.15 degrees. In his paper Observations of two persistent degrees on a thermometer, he recounted his experiments showing that the point of ice is essentially unaffected by pressure. He also determined with precision how the boiling point of water varied as a function of atmospheric pressure. He proposed that the point of his temperature scale, being the boiling point. This pressure is known as one standard atmosphere, the BIPMs 10th General Conference on Weights and Measures later defined one standard atmosphere to equal precisely 1013250dynes per square centimetre. On 19 May 1743 he published the design of a mercury thermometer, in 1744, coincident with the death of Anders Celsius, the Swedish botanist Carolus Linnaeus reversed Celsiuss scale. In it, Linnaeus recounted the temperatures inside the orangery at the University of Uppsala Botanical Garden, since the 19th century, the scientific and thermometry communities worldwide referred to this scale as the centigrade scale. Temperatures on the scale were often reported simply as degrees or. More properly, what was defined as centigrade then would now be hectograde.2 gradians, for scientific use, Celsius is the term usually used, with centigrade otherwise continuing to be in common but decreasing use, especially in informal contexts in English-speaking countries
19.
Cairo
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Cairo is the capital and largest city of Egypt. Cairo has long been a center of the political and cultural life. Cairo has the oldest and largest film and music industries in the Arab world, as well as the worlds second-oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city, with a population of 6.76 million spread over 453 square kilometers, Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live in proximity to the city. Cairo, like many other mega-cities, suffers from high levels of pollution, Cairos metro, one of only two in Africa, ranks among the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, Egyptians often refer to Cairo as Maṣr, the Egyptian Arabic name for Egypt itself, emphasizing the citys importance for the country. In Coptic the city is known as Kahire, meaning Place of the Sun, possibly referring to the ancient city of Heliopolis, the location of the ancient city is the suburb of Ain Shams. The ancient Egyptian name for the area is thought to be Khere-Ohe, The Place of Combat, sometimes the city is informally referred to as Kayro. The area around present-day Cairo, especially Memphis, had long been a point of Ancient Egypt due to its strategic location just upstream from the Nile Delta. However, the origins of the city are generally traced back to a series of settlements in the first millennium. Around the turn of the 4th century, as Memphis was continuing to decline in importance and this fortress, known as Babylon, remained the nucleus of the Roman, and, later, the Byzantine, city and is the oldest structure in the city today. It is also situated at the nucleus of the Coptic Orthodox community, many of Cairos oldest Coptic churches, including the Hanging Church, are located along the fortress walls in a section of the city known as Coptic Cairo. Following the Muslim conquest in 640 AD the conqueror Amr ibn As settled to the north of the Babylon in an area became known as al-Fustat. Originally a tented camp Fustat became a permanent settlement and the first capital of Islamic Egypt, in 750, following the overthrow of the Ummayad caliphate by the Abbasids, the new rulers created their own settlement to the northeast of Fustat which became their capital. This was known as al-Askar as it was laid out like a military camp, a rebellion in 869 by Ahmad ibn Tulun led to the abandonment of Al Askar and the building of another settlement, which became the seat of government. This was al-Qattai, to the north of Fustat and closer to the river, Al Qattai was centred around a palace and ceremonial mosque, now known as the Mosque of ibn Tulun. In 905 the Abbasids re-asserted control of the country and their returned to Fustat
20.
Egypt
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Egypt, officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia by a land bridge formed by the Sinai Peninsula. Egypt is a Mediterranean country bordered by the Gaza Strip and Israel to the northeast, the Gulf of Aqaba to the east, the Red Sea to the east and south, Sudan to the south, and Libya to the west. Across the Gulf of Aqaba lies Jordan, and across from the Sinai Peninsula lies Saudi Arabia, although Jordan and it is the worlds only contiguous Afrasian nation. Egypt has among the longest histories of any country, emerging as one of the worlds first nation states in the tenth millennium BC. Considered a cradle of civilisation, Ancient Egypt experienced some of the earliest developments of writing, agriculture, urbanisation, organised religion and central government. One of the earliest centres of Christianity, Egypt was Islamised in the century and remains a predominantly Muslim country. With over 92 million inhabitants, Egypt is the most populous country in North Africa and the Arab world, the third-most populous in Africa, and the fifteenth-most populous in the world. The great majority of its people live near the banks of the Nile River, an area of about 40,000 square kilometres, the large regions of the Sahara desert, which constitute most of Egypts territory, are sparsely inhabited. About half of Egypts residents live in areas, with most spread across the densely populated centres of greater Cairo, Alexandria. Modern Egypt is considered to be a regional and middle power, with significant cultural, political, and military influence in North Africa, the Middle East and the Muslim world. Egypts economy is one of the largest and most diversified in the Middle East, Egypt is a member of the United Nations, Non-Aligned Movement, Arab League, African Union, and Organisation of Islamic Cooperation. Miṣr is the Classical Quranic Arabic and modern name of Egypt. The name is of Semitic origin, directly cognate with other Semitic words for Egypt such as the Hebrew מִצְרַיִם, the oldest attestation of this name for Egypt is the Akkadian
21.
Father of All Bombs
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The bomb is reportedly four times as powerful as the US militarys GBU-43/B Massive Ordnance Air Blast bomb. This Russian device would therefore be the most powerful weapon in the world. The veracity of Russias claims concerning the size and power have been questioned by US defense analysts. FOAB was successfully field-tested in the evening of September 11,2007. The new weapon is to replace several types of nuclear bombs in its arsenal. The thermobaric device yields the equivalent of 44 tons of TNT using about seven tons of a new type of high explosive, because of this, the bombs blast and pressure wave have a similar effect to a small tactical nuclear weapon, although on a smaller scale. The bomb works by detonating in mid-air, most damage is inflicted by a supersonic shockwave and extremely high temperatures. Thermobaric weapons differ from conventional weapons in that they generate a longer. In doing so, they produce more damage over an area than a conventional weapon of similar mass. According to General Alexander Rushkin, the Russian deputy chief of staff, in comparison, the MOAB produces the equivalent of 11 tons of TNT from 8 tons of high explosive. The blast radius of the FOAB is 3000 meters, almost double that of the MOAB, some defense analysts question both the yield of the bomb and whether it could be deployed by a Tupolev Tu-160 bomber. There are also questions on what type of explosives it used and they quoted Tom Burky, a senior research scientist at Battelle, saying Its not even clear what kind of weapon the Russians tested. He questions if it was what some call a fuel-air explosive or if it was a thermobaric weapon. Fuel-air and thermobaric bombs differ in usefulness, Burky says that the weapon depicted in the video appears to be a fuel-air explosive, based on its shape. German military analyst Sascha Lange speaking at Deutsche Welle pointed out multiple discrepancies of the released video, john Pike, an analyst at the think tank GlobalSecurity, says he believes the weapon is roughly as powerful as the Russians claim. What he does not necessarily believe is that the weapon is new and he says the Russians have possessed a range of thermobaric weapons for at least four decades. Pike says These are fuel-air explosives, designed to generate intense blast pressure over a large area and it is reported that the Russian bomb is a so-called thermobaric bomb that produces both blast and heat. The Russian military has been a pioneer in the development and use of thermobaric weapons
22.
Tomahawk (missile)
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The Tomahawk is a long-range, all-weather, subsonic cruise missile named after the Native American axe. Introduced by McDonnell Douglas in the 1970s, it was designed as a medium to long-range. It has been improved several times, and after corporate divestitures, some Tomahawks were also manufactured by General Dynamics. The Tomahawk missile family consists of a number of subsonic, jet engine-powered missiles designed to attack a variety of surface targets, although a number of launch platforms have been deployed or envisaged, only sea launched variants are currently in service. Tomahawk has a design, allowing a wide variety of warhead, guidance. The Tomahawk project was awarded to Applied Physics Laboratory in Laurel. James H. Walker led a team of scientists to design, the original design with advanced technology is still used today. There have been variants of the BGM-109 Tomahawk employing various types of warheads. BGM-109A Tomahawk Land Attack Nuclear - Not deployed, bGM-109A Tomahawk Land Attack Missile – Nuclear with a W80 thermonuclear weapon. Retired from service sometime between 2010 and 2013, rGM/UGM-109B Tomahawk Anti Ship Missile – active radar homing anti-ship missile variant, withdrawn from service in the 1990s. BGM-109C Tomahawk Land Attack Missile – Conventional with a unitary warhead and this was initially a modified Bullpup warhead. BGM-109D Tomahawk Land Attack Missile – Dispenser with cluster munitions, rGM/UGM-109E Tomahawk Land Attack Missile – improved version of the TLAM-C. BGM-109G Ground Launched Cruise Missile – with a W84 nuclear warhead, aGM-109H/L Medium Range Air to Surface Missile – a shorter range, turbojet powered ASM with cluster munitions, never entered service, cost US$569,000. Many of the versions were converted into TLAMs at the end of the Cold War. The Block III TLAMs that entered service in 1993 can fly farther, Block IV TLAMs are completely redesigned with an improved turbofan engine. The F107-402 engine provided the new BLK III with a throttle control and this engine also provided better fuel economy. The Block IV TLAMs have enhanced capabilities and are equipped with a real-time targeting system for striking fleeting targets. A major improvement to the Tomahawk is network-centric warfare-capabilities, using data from sensors to find its target
23.
MythBusters
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MythBusters is a science entertainment television program created by Peter Rees and produced by Australias Beyond Television Productions. The series premiered on the Discovery Channel on January 23,2003, the series was transmitted by numerous international broadcasters, including SBS Australia, and other Discovery channels worldwide. The show was one of the oldest—and the most popular—on Discovery Channel, being preceded only by How Its Made and Daily Planet, from 2006 to 2016, the show was overseen by British show-runner Dan Tapster, working out of Sydney, San Francisco and Manchester. Filmed in San Francisco and edited in Artarmon, New South Wales, Australia, during the second season, members of Savage and Hynemans behind-the-scenes team were organized into a second team of MythBusters. They generally tested myths separately from the duo and operated from another workshop. On October 21,2015, it was announced that MythBusters would air its 14th, the show aired its final episode on March 6,2016. On March 25, Discoverys sister network, Science, announced its intention of continuing the series with new hosts, the show, currently airing, is titled Mythbusters, The Search. Adam Savage has confirmed that he and his former cohosts have no intentions of reuniting for future team projects, MythBusters refers both to the name of the documentary and also the cast members who test the experiments. The series concept was created for the Discovery Channel as Tall Tales or True by Australian writer and producer Peter Rees of Beyond Productions in 2002, Discovery rejected the proposal initially because they had just commissioned a series on the same topic. Rees refined the pitch to focus on testing key elements of the rather than just retelling them. Discovery agreed to develop and co-produce a three-episode series pilot, Jamie Hyneman was one of a number of special effects artists who were asked to prepare a casting video for network consideration. Rees had interviewed him previously for a segment of the science series Beyond 2000 about the British/American robot combat television series Robot Wars. The highest rated regular episode featured two stories, straw through a tree, and talking to plants. The highest rated two hour special was Hollywood Myths, the highest rated Shark Week special was Jaws Myths which screened in 2005. During July 2006, an edited version of MythBusters began airing on BBC Two in the UK. The episodes shown on the European Discovery Channel sometimes include extra scenes not shown in the United States version, the 14th season, which premiered in January 2016, was the final season for the series. Adam Savage and Jamie Hyneman are the original MythBusters, and initially explored all the myths of the series using their experience with special effects. The two work at Hynemans effects workshop, M5 Industries, they use of his staff
24.
ANFO
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ANFO is a widely used bulk industrial explosive. It consists of 94% porous prilled ammonium nitrate, which acts as the agent and absorbent for the fuel. ANFO is also used in avalanche hazard mitigation. It accounts for an estimated 80% of the 2. 7×109 kg of explosives used annually in North America, the press and other media have used the term ANFO loosely and imprecisely in describing IEDs, in cases of fertilizer bombs. The use of ANFO originated in the 1950s, the chemistry of ANFO detonation is the reaction of ammonium nitrate with a long-chain alkane to form nitrogen, carbon dioxide, and water. In an ideal stoichiometrically balanced reaction, ANFO is composed of about 94. 3% AN and 5. 7% FO by weight, in practice, a slight excess of fuel oil is added, as underdosing results in reduced performance while overdosing merely results in more post-blast fumes. When detonation conditions are optimal, the gases are the only products. In practical use, such conditions are impossible to attain, and blasts produce moderate amounts of gases such as carbon monoxide. The fuel component of ANFO is typically diesel, but kerosene, coal dust, racing fuel, finely powdered aluminium in the mixture will sensitise it to detonate more readily. ANFO is classified as an explosive, meaning that it decomposes through detonation rather than deflagration at a velocity higher than the speed of sound in the material. ANFO has a moderate velocity compared to other explosives, measuring 3,200 m/s in 130 mm diameter, unconfined. ANFO is an explosive, meaning that it cannot be set off by the small quantity of primary explosive in a typical blasting cap. A larger quantity of explosive, known as a primer or a booster. One or two sticks of dynamite were used, current practice is to use Tovex or cast boosters of pentolite. In the mining industry, the term ANFO specifically describes a mixture of ammonium nitrate prills. Other explosives based on the ANFO chemistry exist, the most commonly used are emulsions and they differ from ANFO in the physical form the reactants take. The most notable properties of emulsions are water resistance and higher bulk density, while the density of pure crystalline ammonium nitrate is 1700 kg/m3, individual prills of explosive-grade AN measure approximately 1300 kg/m3. Their lower density is due to the presence of a spherical air pocket within each prill
25.
Operation Sailor Hat
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Operation Sailor Hat was a series of three tests of explosives effects, conducted by the United States Navy on the island of Kahoʻolawe, Hawaii in 1965. They were non–nuclear tests employing large quantities of explosives to simulate the effects of a nuclear weapon blast. In addition, seismological data, underwater acoustics, radio communications, cratering, air blast effects, cloud growth, fireball generation and these were a mixture of the obsolete, Atlanta being built during WWII and decommissioned in 1965, and the recently constructed. Each Sailor Hat test consisted of a dome-stacked 500-ton charge of TNT high explosive detonated on the shore of Kahoʻolawe close to the ships under test, each test saw the USS Atlanta move closer to the explosion. The first test, called Bravo, occurred on 6 February 1965, with the second test, called Charlie, on 16 April and the last, codenamed Delta, on 19 June. Cameras recorded the blast effects inside the ships and have shown that the force of the blast was enough to buckle steel walls and tear off heavy radar equipment, although severely damaged, the ships stayed afloat. In addition, two observation blimps were destroyed high above ground by the shock wave, USS England, which was farthest from the blast center, experienced the least damage, the most serious of which was only a dent where a boulder had hit the ship. The crater left by the blast is called the Sailors Hat crater and holds a pool containing Halocaridina rubra shrimp. Photos of the Sailor Hat test in 1965, archived from the original on July 22,2012. YouTube video of Operation Sailor Hat
26.
Oppau explosion
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The plant began producing ammonium sulfate in 1911, but during World War I when Germany was unable to obtain the necessary sulfur, it began to produce ammonium nitrate as well. Ammonia could be produced without overseas resources, using the Haber process, the workers needed to use pickaxes to get it out, a problematic situation because they could not enter the silo and risk being buried in collapsing fertilizer. To ease their work, small charges of dynamite were used to loosen the mixture, indeed, nothing extraordinary happened during an estimated 20,000 firings, until the fateful explosion on September 21. As all involved died in the explosion, the causes are not clear, changes in humidity and density also significantly affect the explosive properties. A few months before the incident, the process had been changed in such a way as to lower the humidity level of the mixture from 3-4% to 2%. Both these factors rendered it more likely to explode, there is also evidence that the lot of mixture in question was not of uniform composition and may have contained pockets of up to several dozen tonnes of mixture enriched in ammonium nitrate. The explanation is proposed that one of the charges was by chance placed in such a pocket. Two months earlier, at Kriewald, then part of Germany,19 people had died when 30 tonnes of ammonium nitrate were detonated by people doing the same thing and it is not clear why this warning was not heeded. The explosion was estimated to be about 1–2 kilotonnes TNT equivalent, in Heidelberg, traffic was stopped by the mass of broken glass on the streets, a tramway got derailed and even here some roofs were ripped off. About 80 percent of all buildings in Oppau were destroyed, leaving 6,500 homeless, at ground zero a 90 m by 125 m crater,19 m deep, was created. Damages were estimated by the New York Times in 1922 at then 321 million Marks, according to some descriptions, only 450 tonnes exploded, out of 4,500 tonnes of fertilizer stored in the warehouse. Ammonium nitrate disasters List of the largest artificial non-nuclear explosions Photo of the Oppau explosion Deutsche Welle
27.
Halifax Explosion
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The Halifax Explosion was a maritime disaster in Halifax, Nova Scotia, Canada, on the morning of 6 December 1917. SS Mont-Blanc, a French cargo ship laden with explosives, collided with the Norwegian vessel SS Imo in the Narrows. A fire on board the French ship ignited her cargo, causing an explosion that devastated the Richmond district of Halifax. Approximately 2,000 people were killed by blast, debris, fires and collapsed buildings, the blast was the largest man-made explosion prior to the development of nuclear weapons, releasing the equivalent energy of roughly 2.9 kilotons of TNT. Mont-Blanc was under orders from the French government to carry her cargo of explosives from New York via Halifax to Bordeaux. At roughly 8,45 am, she collided at low speed – approximately one knot – with the unladen Imo, the resulting fire aboard the French ship quickly grew out of control. Approximately 20 minutes later at 9,04,35 am, nearly all structures within an 800-metre radius, including the entire community of Richmond, were obliterated. A pressure wave snapped trees, bent iron rails, demolished buildings, grounded vessels, hardly a window in the city proper survived the blast. Across the harbour, in Dartmouth, there was widespread damage. A tsunami created by the blast wiped out the community of Mikmaq First Nations people who had lived in the Tufts Cove area for generations, Relief efforts began almost immediately, and hospitals quickly became full. Rescue trains began arriving from across eastern Canada and the north-eastern United States, construction of temporary shelters to house the many people left homeless began soon after the disaster. The initial judicial inquiry found Mont-Blanc to have responsible for the disaster. There are several memorials to the victims of the explosion in the North End, the community of Dartmouth lies on the east shore of Halifax Harbour, while Halifax is on the west shore. After 1906, the Canadian Government took over the Halifax Dockyard from the Royal Navy and this dockyard later became the command centre of the Royal Canadian Navy upon its founding in 1910. Just before the First World War, the Canadian government began to make a determined, costly effort to develop the harbour, the outbreak of the war brought Halifax back to prominence. The population of Halifax/Dartmouth had increased to between 60,000 and 65,000 people by 1917, convoys carried soldiers, men, animals and supplies to the European theatre of war. The two main points of departure were in Nova Scotia at Sydney in Cape Breton and Halifax, Hospital ships brought the wounded to the city, and a new military hospital was constructed in the city. The success of German U-boat attacks on crossing the Atlantic Ocean led the Allies to institute a convoy system to reduce losses while transporting goods
28.
Little Boy
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It was the first atomic bomb to be used in warfare. The Hiroshima bombing was the second artificial nuclear explosion in history, after the Trinity test, and it exploded with an energy of approximately 15 kilotons of TNT. The bomb caused significant destruction to the city of Hiroshima, Little Boy was developed by Lieutenant Commander Francis Birchs group of Captain William S. Parsonss Ordnance Division at the Manhattan Projects Los Alamos Laboratory during World War II. Parsons flew on the Hiroshima mission as weaponeer, the Little Boy was a development of the unsuccessful Thin Man nuclear bomb. Like Thin Man, it was a fission weapon. This was accomplished by shooting a hollow cylinder of enriched uranium onto a cylinder of the same material by means of a charge of nitrocellulose propellant powder. It contained 64 kg of enriched uranium, of less than a kilogram underwent nuclear fission. Its components were fabricated at three different plants so that no one would have a copy of the complete design, the Navy Bureau of Ordnance built another 25 Little Boy assemblies in 1947 for use by the Lockheed P2V Neptune nuclear strike aircraft. All the Little Boy units were withdrawn from service by the end of January 1951, according to Serber, he chose them based on their design shapes. The Thin Man was a device, and its name came from the Dashiell Hammett detective novel. The Fat Man was round and fat, and was named after Sydney Greenstreets Kasper Gutman character in The Maltese Falcon, Little Boy came last, and was named after Elisha Cook, Jr. s character in the same film, as referred to by Humphrey Bogart. Because uranium-235 was known to be fissionable, it was the first approach to bomb development pursued, as the first design developed, it is sometimes known as the Mark I. The vast majority of the came in the form of the isotope enrichment of the uranium necessary for the weapon. Enrichment was performed at Oak Ridge, Tennessee, where the separation plant, known as Y-12. The first shipments of enriched uranium were sent to the Los Alamos Laboratory in June 1944. At least part of the 1,200 long tons of uranium ore, Little Boy was a simplification of Thin Man, the previous gun-type fission weapon design. Thin Man,17 feet long, was designed to use plutonium, in July 1944, almost all research at Los Alamos was redirected to the implosion-type plutonium weapon. Overall responsibility for the uranium gun-type weapon was assigned to Captain William S. Parsonss Ordnance Division, all the design, development, and technical work at Los Alamos was consolidated under Lieutenant Commander Francis Birchs group
29.
Hiroshima
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Hiroshima is the capital of Hiroshima Prefecture and the largest city in the Chūgoku region of western Honshu - the largest island of Japan. The citys name, 広島, means Broad Island in Japanese, Hiroshima gained city status on April 1,1889. On April 1,1980, Hiroshima became a designated city, as of August 2016, the city had an estimated population of 1,196,274. The GDP in Greater Hiroshima, Hiroshima Metropolitan Employment Area, is US$61.3 billion as of 2010, kazumi Matsui has been the citys mayor since April 2011. Hiroshima was established on the river delta coastline of the Seto Inland Sea in 1589 by powerful warlord Mōri Terumoto, Hiroshima Castle was quickly built, and in 1593 Terumoto moved in. Terumoto was on the side at the Battle of Sekigahara. The winner of the battle, Tokugawa Ieyasu, deprived Mōri Terumoto of most of his fiefs, including Hiroshima and gave Aki Province to Masanori Fukushima, after the han was abolished in 1871, the city became the capital of Hiroshima Prefecture. Hiroshima became an urban center during the imperial period, as the Japanese economy shifted from primarily rural to urban industries. During the 1870s, one of the seven government-sponsored English language schools was established in Hiroshima, Ujina Harbor was constructed through the efforts of Hiroshima Governor Sadaaki Senda in the 1880s, allowing Hiroshima to become an important port city. The Sanyō Railway was extended to Hiroshima in 1894, and a line from the main station to the harbor was constructed for military transportation during the First Sino-Japanese War. During that war, the Japanese government moved temporarily to Hiroshima, New industrial plants, including cotton mills, were established in Hiroshima in the late 19th century. Further industrialization in Hiroshima was stimulated during the Russo-Japanese War in 1904, the Hiroshima Prefectural Commercial Exhibition Hall was constructed in 1915 as a center for trade and exhibition of new products. Later, its name was changed to Hiroshima Prefectural Product Exhibition Hall, during World War I, Hiroshima became a focal point of military activity, as the Japanese government entered the war on the Allied side. About 500 German prisoners of war were held in Ninoshima Island in Hiroshima Bay, during World War II, the 2nd General Army and Chugoku Regional Army were headquartered in Hiroshima, and the Army Marine Headquarters was located at Ujina port. The city also had large depots of supplies, and was a key center for shipping. The bombing of Tokyo and other cities in Japan during World War II caused widespread destruction, there were no such air raids on Hiroshima. However, a real threat existed and was recognized, in order to protect against potential firebombings in Hiroshima, school children aged 11–14 years were mobilized to demolish houses and create firebreaks. On Monday, August 6,1945, at 8,15 a. m, by the end of the year, injury and radiation brought the total number of deaths to 90, 000–166,000
30.
Nagasaki
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Nagasaki is the capital and the largest city of Nagasaki Prefecture on the island of Kyushu in Japan. Part of Nagasaki was home to a major Imperial Japanese Navy base during the First Sino-Japanese War, during World War II, the American atomic bombings of Hiroshima and Nagasaki made Nagasaki the second and, to date, last city in the world to experience a nuclear attack. As of 1 January 2009, the city has an population of 446,007. The total area is 406.35 km², a small fishing village set in a secluded harbor, Nagasaki had little historical significance until contact with Portuguese explorers in 1543. An early visitor was Fernão Mendes Pinto, who came on a Portuguese ship which landed nearby in Tanegashima and his followers who remained behind converted a number of daimyōs. The most notable among them was Ōmura Sumitada, the little harbor village quickly grew into a diverse port city, and Portuguese products imported through Nagasaki were assimilated into popular Japanese culture. The Portuguese also brought them many goods from China. Thus, for a period after 1580, the city of Nagasaki was a Jesuit colony, under their administrative. It was administered by the captain of the Portuguese black ship, the highest representative of the Portuguese Crown and it became a refuge for Christians escaping maltreatment in other regions of Japan. In 1587, however, Toyotomi Hideyoshis campaign to unify the country arrived in Kyūshū, however, the expulsion order went largely unenforced, and the fact remained that most of Nagasakis population remained openly practicing Catholic. In 1596, the Spanish ship San Felipe was wrecked off the coast of Shikoku, in response, Hideyoshi ordered the crucifixions of twenty-six Catholics in Nagasaki on February 5 of that year. Portuguese traders were not ostracized, however, and so the city continued to thrive, in 1602, Augustinian missionaries also arrived in Japan, and when Tokugawa Ieyasu took power in 1603, Catholicism was still tolerated. Many Catholic daimyōs had been allies at the Battle of Sekigahara. Once Osaka Castle had been taken and Toyotomi Hideyoshis offspring killed, though, in addition, the Dutch and English presence allowed trade without religious strings attached. Thus, in 1614, Catholicism was officially banned and all missionaries ordered to leave, most Catholic daimyo apostatized, and forced their subjects to do so, although a few would not renounce the religion and left the country for Macau, Luzon and Japantowns in Southeast Asia. A brutal campaign of persecution followed, with thousands of converts across Kyūshū and other parts of Japan killed, tortured, catholicisms last gasp as an open religion and the last major military action in Japan until the Meiji Restoration was the Shimabara Rebellion of 1637. Consequently, in Tokugawa society the word Shimabara solidified the connection between Christianity and disloyalty, constantly used again and again in Tokugawa propaganda, the Shimabara Rebellion also convinced many policy-makers that foreign influences were more trouble than they were worth, leading to the national isolation policy. The Great Fire of Nagasaki destroyed much of the city in 1663, including the Mazu shrine at the Kofukuji Temple patronized by the Chinese sailors, in 1720 the ban on Dutch books was lifted, causing hundreds of scholars to flood into Nagasaki to study European science and art
31.
Nuclear weapon yield
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An explosive yield of one terajoule is 0.239 kt of TNT. The yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon, the practical maximum yield-to-weight ratio for fusion weapons has been estimated to six megatons of TNT per metric ton of bomb mass. Yields of 5.2 megatons/ton and higher have been reported for large weapons constructed for use in the early 1960s. Most artificial non-nuclear explosions are considerably smaller than even what are considered to be very small nuclear weapons, the yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. According to nuclear-weapons designer Ted Taylor, the practical maximum yield-to-weight ratio for fusion weapons is about 6 megatons of TNT per metric ton. The Taylor limit is not derived from first principles, and weapons with yields as high as 9.5 megatons per metric ton have been designed and built. The 25 Mt yield option reported for the B41 would give it a ratio of 5.1 megatons of TNT per metric ton. This results in the B41 still retaining the record for the highest Yield-to-weight weapon ever designed, in 1963 DOE declassified statements that the U. S. had the technological capability of deploying a 35 Mt warhead on the Titan II, or a 50-60 Mt gravity bomb on B-52s. Neither weapon was pursued, but either would require yield-to-weight ratios superior to a 25 Mt Mk-41, for current smaller US weapons, yield is 600 to 2200 kilotons of TNT per metric ton. By comparison, for the very small devices such as the Davy Crockett it was 0.4 to 40 kilotons of TNT per metric ton. For historical comparison, for Little Boy the yield was only 4 kilotons of TNT per metric ton, and for the largest Tsar Bomba, the yield was 2 megatons of TNT per metric ton. The largest pure-fission bomb ever constructed Ivy King had a 500 kiloton yield, however, there is no known upper yield limit for a fusion bomb. For example, the Mk-36 bomb as built had a ratio of 1.25 megatons of TNT per metric ton. Delivery size limits can be estimated to ascertain limits to delivery of high yield weapons. If the full 250 metric ton payload of the Antonov An-225 aircraft could be used, likewise, the maximum limit of a missile-delivered weapon is determined by the missile gross payload capacity. The large Russian SS-18 ICBM has a capacity of 7,200 kg. A Saturn V-scale missile could deliver over 120 tons, giving a maximum yield of about 700 megatons. The following list is of nuclear explosions
32.
B83 nuclear bomb
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The B83 thermonuclear weapon is a variable-yield gravity bomb developed by the United States in the late 1970s, entering service in 1983. With a maximum yield of 1.2 megatonnes of TNT and it was designed at Lawrence Livermore National Laboratory, and the first underground test detonation of the production B83 took place on 15 December 1984. The B83 was based partly on the earlier B77 program, which was terminated because of cost overruns, the B77 was designed with an active altitude control and lifting parachute system for supersonic low-altitude delivery from the B-1A bomber. The B83 replaced several earlier weapons, including the B28, B43 and it was the first U. S. nuclear weapon designed from the start to avoid accidental detonation, with the use of insensitive explosives in the trigger lens system. Its layout is similar to that of the smaller B61, with the warhead mounted in the part of the weapon to make the bomb nose-heavy. It was intended for high-speed carriage and delivery at high or low altitude, for the latter role, it is equipped with a parachute retardation system, with a 14-meter Kevlar ribbon parachute capable of rapid deceleration. It can be employed in free-fall, retarded, contact, and laydown modes, security features include next-generation permissive action link and a command disablement system, rendering the weapon tactically useless without a nuclear yield. The B83 was reportedly test fired in the Grenadier Tierra nuclear weapon test on 15 December 1984, as of 2015, the B83 is being considered for reduction in the US nuclear arsenal as a part of a modernization and downsizing program begun in approximately 2010. The bomb is 3.7 meters long, with a diameter of 460 millimeters, the actual nuclear explosive package, judging from published drawings, occupies some 0.91 to 1.22 m in the forward part of the bomb case. The bomb weighs approximately 1,100 kilograms, the location of the lifting lugs shows that the greater part of the total mass is contained in the nuclear explosive. It has a yield, the destructive power is adjustable from somewhere in the low kiloton range up to a maximum of 1.2 megatons. The weapon is protected by a Category D Permissive Action Link About 650 B83s were built, all A-6, A-7 and FB-111 aircraft have been withdrawn from service and retired. The B83 is one of the weapons considered for use in the Nuclear Bunker Buster project, while most efforts have focused on the smaller B61-11 nuclear bomb, Los Alamos National Laboratory was also analyzing the use of the B83 in this role. The physics package contained within the B83 has been studied for use in asteroid impact avoidance strategies against any seriously threatening near earth asteroids. Six such warheads, configured for the maximum 1.2 Mt yield, would be deployed by maneuvering space vehicles to knock an asteroid off course, in the 1996 film Broken Arrow, two B83 bombs are stolen. In the strategy game World in Conflict, a B83 is considered the last resort if the U. S. Army failed to retake Seattle from the Soviet Union before the arrival of the PLA naval forces. In the 2007 film Aliens vs. Predator, Requiem, a B83 bomb is used to destroy a city, in the Charles Stross alternate-history novel The Revolution Trade, a version of the post-9/11 U. S. carpet bombs a trans-dimensional enemy state using hundreds of B83s. B61 nuclear bomb List of nuclear weapons B83 Information Site B83 page at nuclearweaponarchive. org NASA proposal to attack asteroids
33.
Tunguska event
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The Tunguska event was a large explosion that occurred near the Stony Tunguska River, in Yeniseysk Governorate, Russia, on the morning of 30 June 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 km2 of forest yet caused no known human casualties, the explosion is generally attributed to the air burst of a meteoroid. The Tunguska event is the largest impact event on Earth in recorded history, studies have yielded different estimates of the meteoroids size, on the order of 60 to 190 metres, depending on whether the body was a comet or a denser asteroid. Since the 1908 event, there have been an estimated 1,000 scholarly papers published on the Tunguska explosion. In 2013, a team of researchers published results of micro-samples from a peat bog near the center of the affected area showing fragments that may be of meteoritic origin. An explosion of this magnitude would be capable of destroying a large metropolitan area and this event has helped to spark discussion of asteroid impact avoidance. About ten minutes later, there was a flash and a similar to artillery fire. Eyewitnesses closer to the explosion reported that the source of the sound moved from the east to the north of them, the sounds were accompanied by a shock wave that knocked people off their feet and broke windows hundreds of kilometres away. The majority of witnesses reported only the sounds and tremors, eyewitness accounts vary regarding the sequence and duration of the events. The explosion registered at seismic stations across Eurasia and it is estimated that, in some places, the resulting shock wave was equivalent to an earthquake measuring 5.0 on the Richter magnitude scale. It also produced fluctuations in atmospheric pressure strong enough to be detected in Great Britain, testimony of S. Semenov, as recorded by Leonid Kuliks expedition in 1930, At breakfast time I was sitting by the house at Vanavara Trading Post, facing north. I suddenly saw that directly to the north, over Onkouls Tunguska Road, the split in the sky grew larger, and the entire northern side was covered with fire. At that moment I became so hot that I couldnt bear it, as if my shirt was on fire, from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, I lost my senses for a moment, but then my wife ran out and led me to the house. After that such noise came, as if rocks were falling or cannons were firing, the earth shook, and when I was on the ground, I pressed my head down, fearing rocks would smash it. When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, later we saw that many windows were shattered, and in the barn a part of the iron lock snapped. Testimony of Chuchan of Shanyagir tribe, as recorded by I. M. Suslov in 1926, suddenly we both woke up at the same time. We heard whistling and felt strong wind, Chekaren said, Can you hear all those birds flying overhead
34.
Tropical cyclone
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Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane, typhoon /taɪˈfuːn/, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface and this energy source differs from that of mid-latitude cyclonic storms, such as noreasters and European windstorms, which are fueled primarily by horizontal temperature contrasts. The strong rotating winds of a tropical cyclone are a result of the conservation of momentum imparted by the Earths rotation as air flows inwards toward the axis of rotation. As a result, they form within 5° of the equator. Tropical cyclones are typically between 100 and 2,000 km in diameter, Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their nature, with wind blowing counterclockwise in the Northern Hemisphere. The opposite direction of circulation is due to the Coriolis effect, in addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes. They typically weaken rapidly over land where they are cut off from their energy source. For this reason, coastal regions are vulnerable to damage from a tropical cyclone as compared to inland regions. Heavy rains, however, can cause significant flooding inland, though their effects on human populations are often devastating, tropical cyclones can relieve drought conditions. They also carry heat away from the tropics and transport it toward temperate latitudes. Tropical cyclones are areas of low pressure in the troposphere. On Earth, the pressures recorded at the centers of tropical cyclones are among the lowest ever observed at sea level, the environment near the center of tropical cyclones is warmer than the surroundings at all altitudes, thus they are characterized as warm core systems. The near-surface wind field of a cyclone is characterized by air rotating rapidly around a center of circulation while also flowing radially inwards. At the outer edge of the storm, air may be nearly calm, however, due to the Earths rotation, as air flows radially inward, it begins to rotate cyclonically in order to conserve angular momentum. At an inner radius, air begins to ascend to the top of the troposphere and this radius is typically coincident with the inner radius of the eyewall, and has the strongest near-surface winds of the storm, consequently, it is known as the radius of maximum winds. Once aloft, air flows away from the center, producing a shield of cirrus clouds
35.
Antiproton
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The antiproton, p, is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause particles to be annihilated in a burst of energy. The existence of the antiproton with −1 electric charge, opposite to the +1 electric charge of the proton, was predicted by Paul Dirac in his 1933 Nobel Prize lecture, in terms of valence quarks, an antiproton consists of two up antiquarks and one down antiquark. Antiprotons have been detected in cosmic rays for over 25 years, first by balloon-borne experiments and their energy spectrum is modified by collisions with other atoms in the interstellar medium, and antiprotons can also be lost by leaking out of the galaxy. The antiproton cosmic ray energy spectrum is now measured reliably and is consistent with this picture of antiproton production by cosmic ray collisions. This also provides a limit on the antiproton lifetime of about 1-10 million years. Since the galactic storage time of antiprotons is about 10 million years and this is significantly more stringent than the best laboratory measurements of the antiproton lifetime, LEAR collaboration at CERN,0.08 years Antihydrogen Penning trap of Gabrielse et al. CPT symmetry is a consequence of quantum field theory and no violations of it have ever been detected. BESS, balloon-borne experiment, flown in 1993,1995,1997,2000,2002,2004 and 2007, CAPRICE, balloon-borne experiment, flown in 1994 and 1998. HEAT, balloon-borne experiment, flown in 2000, AMS, space-based experiment, prototype flown on the space shuttle in 1998, intended for the International Space Station, launched May 2011. PAMELA, satellite experiment to detect cosmic rays and antimatter from space, recent report discovered 28 antiprotons in the South Atlantic Anomaly. Antiprotons are routinely produced at Fermilab for collider physics operations in the Tevatron, the use of antiprotons allows for a higher average energy of collisions between quarks and antiquarks than would be possible in proton-proton collisions. This is because the valence quarks in the proton, and the valence antiquarks in the antiproton and their formation requires energy equivalent to a temperature of 10 trillion K and this does not tend to happen naturally. However, at CERN, protons are accelerated in the Proton Synchrotron to an energy of 26 GeV, the protons bounce off the iridium nuclei with enough energy for matter to be created. A range of particles and antiparticles are formed, and the antiprotons are separated off using magnets in vacuum, in July 2011, the ASACUSA experiment at CERN determined the mass of the antiproton to be 1836.1526736 times more massive than an electron. This is the same as the mass of a proton, within the level of certainty of the experiment, antiprotons have been shown within laboratory experiments to have the potential to treat certain cancers, in a similar method currently used for ion therapy. The primary difference between therapy and proton therapy is that following ion energy deposition the antiproton annihilates depositing additional energy in the cancerous region. Antimatter Antineutron Positron Antihydrogen Antiprotonic helium List of particles Recycling antimatter
36.
Annihilation
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The total energy and momentum of the initial pair are conserved in the process, and, more generally are distributed among a set of other particles in the final state. Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all numbers of such an original pair are zero. Hence, any set of particles may be produced whose total numbers are also zero as long as conservation of energy. During a low-energy annihilation, photon production is favored, since these particles have no mass, however, high-energy particle colliders produce annihilations where a wide variety of exotic heavy particles are created. The word annihilation may also be used informally for the interaction of two particles that are not mutual antiparticles, some quantum numbers may then not sum to zero in the initial state, but must be conserved, with the same totals in the final state. An example is the annihilation of an electron antineutrino with an electron to produce a W−. If the annihilating particles are composite, such as mesons or baryons, if the initial two particles are elementary, then they may combine to produce only a single elementary boson, such as a photon, gluon, Z, or a Higgs boson. If the total energy in the frame is equal to the rest mass of a real boson. Otherwise, the process is understood as the creation of a boson that is virtual. This is called an s-channel process, an example is the annihilation of an electron with a positron to produce a virtual photon, which converts into a muon and anti-muon. If the energy is enough, a Z could replace the photon. Both the annihilating electron and positron particles have a rest energy of about 0.511 million electron volts, if their kinetic energies are relatively negligible, this total rest energy appears as the photon energy of the gamma rays produced. Each of the gamma rays then has an energy of about 0.511 MeV, momentum and energy are both conserved, with 1.022 MeV of gamma rays moving in opposite directions. If one or both charged particles carry a larger amount of energy, various other particles can be produced. The inverse process, pair production by a real photon, is also possible in the electromagnetic field of a third particle. When a proton encounters its antiparticle, the reaction is not as simple as electron-positron annihilation, unlike an electron, a proton is a composite particle consisting of three valence quarks and an indeterminate number of sea quarks bound by gluons. This type of reaction will occur between any baryon and any antibaryon consisting of three antiquarks, one of which corresponds to a quark in the baryon, antiprotons can and do annihilate with neutrons, and likewise antineutrons can annihilate with protons, as discussed below. Reactions in which proton-antiproton annihilation produces as many as nine mesons have been observed, the generated mesons leave the site of the annihilation at moderate fractions of the speed of light, and decay with whatever lifetime is appropriate for their type of meson
37.
Neutrino
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A neutrino is a fermion that interacts only via the weak subatomic force and gravity. The mass of the neutrino is much smaller than that of the known elementary particles. The neutrino is so named because it is neutral and because its rest mass is so small that it was originally thought to be zero. The weak force has a short range, gravity is extremely weak on the subatomic scale. Thus, neutrinos pass through normal matter unimpeded and undetected. Weak interactions create neutrinos in one of three flavors, electron neutrinos, muon neutrinos, or tau neutrinos, in association with the corresponding charged lepton. Although neutrinos were long believed to be massless, it is now known there are three discrete neutrino masses with different tiny values, but they dont correspond uniquely to the three flavors. A neutrino created with a specific flavor is in a specific quantum superposition of all three mass states. Neutrinos oscillate between different flavors in flight, for example, an electron neutrino produced in a beta decay reaction may interact in a distant detector as a muon or tau neutrino. For each neutrino, there exists a corresponding antiparticle, called an antineutrino. They are distinguished from the neutrinos by having opposite signs of lepton number, the majority of neutrinos in the vicinity of the Earth are from nuclear reactions in the Sun. About 65 billion solar neutrinos per second pass through every square centimeter perpendicular to the direction of the Sun in the region of the Earth, neutrinos are also finding practical applications, such as tomography of the interior of the earth. The neutrino was postulated first by Wolfgang Pauli in 1930 to explain how beta decay could conserve energy, momentum and he considered that the new particle was emitted from the nucleus together with the electron or beta particle in the process of beta decay. James Chadwick discovered a more massive nuclear particle in 1932 and also named it a neutron. However, the journal Nature rejected Fermis paper, saying that the theory was too remote from reality. He submitted the paper to an Italian journal, which accepted it, however, by 1934 there was experimental evidence against Bohrs idea that energy conservation is invalid for beta decay. Such a limit is not expected if the conservation of energy is invalid, Pauli made use of the occasion to publicly emphasize that the still-undetected neutrino must be an actual particle. In 1942, Wang Ganchang first proposed the use of beta capture to experimentally detect neutrinos, in the 20 July 1956 issue of Science, Clyde Cowan, Frederick Reines, F. B
