However, temperature variations on Mars follow the hours of sunlight more closely since the atmosphere is quite thin, and there are no bodies of water to retain heat after dark. Seasonal variations may be more precisely specified by the parameter Ls, which is the areocentric longitude of the Sun. It is an angular measure of the position of a planet in its orbit. So Ls provides a convenient way of measuring the changes in season. Also, solstice means "the Sun stands still", and refers to the observation that near the Summer and Winter Solstice dates, the sunrise and sunset times do not vary appreciably. Given the orbital parameters for both Earth and Mars, one can calculate the values of Ls over a year.
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General Edit "Nuclear winter," or as it was initially termed, "nuclear twilight," began to be considered as a scientific concept in the s, after it became clear that an earlier hypothesis, that fireball generated NOx emissions would devastate the ozone layer , was losing credibility.
It was within this context that the climatic effects of soot from fires became the new focus of the climatic effects of nuclear war. Once the quantity of soot is decided upon by the researchers, the climate effects of these soot clouds are then modeled. Turco in reference to a 1-dimensional computer model created to examine the "nuclear twilight" idea, this 1-D model output the finding that massive quantities of soot and smoke would remain aloft in the air for on the order of years, causing a severe planet-wide drop in temperature.
Turco would later distance himself from these extreme 1-D conclusions. More recently, the same team of prominent modellers from the s have begun again to publish the outputs of computer models, these newer models produce the same general findings as their old ones, that the ignition of firestorms, each comparable in intensity to that observed in Hiroshima in , could produce a "small" nuclear winter. Robock has not modeled this, but has speculated that it would have global agricultural losses as a consequence.
The only phenomenon that is modeled by computer in the nuclear winter papers is the climate forcing agent of firestorm-soot, a product which can be ignited and formed by a myriad of means. These were speculated to be a possible result of any large scale employment of counter-value airbursting nuclear weapon use during an American-Soviet total war.
This larger number of firestorms, which are not in themselves modeled,  are presented as causing nuclear winter conditions as a result of the smoke inputted into various climate models, with the depths of severe cooling lasting for as long as a decade.
Independent of the team that continue to publish theoretical models on nuclear winter, in , Mike Fromm of the Naval Research Laboratory , experimentally found that each natural occurrence of a massive wildfire firestorm, much larger than that observed at Hiroshima, can produce minor "nuclear winter" effects, with short-lived, approximately one month of a nearly immeasurable drop in surface temperatures, confined to the hemisphere that they burned in.
A suite of satellite and aircraft-based firestorm-soot-monitoring instruments are at the forefront of attempts to accurately determine the lifespan, quantity, injection height, and optical properties of this smoke. In , various sensing instruments detected 17 distinct pyrocumulonimbus cloud events in North America alone.
In this scenario it is predicted[ by whom? The modeled stable inversion layer of hot soot between the troposphere and high stratosphere that produces the anti-greenhouse effect was dubbed the "Smokeosphere" by Stephen Schneider et al. Despite the separation in time, ferocity and area burned, leading modelers of the hypothesis state that these five fires potentially placed five percent as much smoke into the stratosphere as the hypothetical nuclear-ignited fires discussed in modern models.
The exact timescale for how long this smoke remains, and thus how severely this smoke affects the climate once it reaches the stratosphere, is dependent on both chemical and physical removal processes. The chemical processes that affect the removal are dependent on the ability of atmospheric chemistry to oxidize the carbonaceous component of the smoke, via reactions with oxidative species such as ozone and nitrogen oxides , both of which are found at all levels of the atmosphere,   and which also occur at greater concentrations when air is heated to high temperatures.
Historical data on residence times of aerosols, albeit a different mixture of aerosols , in this case stratospheric sulfur aerosols and volcanic ash from megavolcano eruptions, appear to be in the one-to-two-year time scale,  however aerosol—atmosphere interactions are still poorly understood.
These partially burnt "organics" as they are known, often form tar balls and brown carbon during common lower-intensity wildfires, and can also coat the purer black carbon particles. It depicts the findings of Soviet 3-D computer model research on nuclear winter from , and although containing similar errors as earlier Western models, it was the first 3-D model of nuclear winter.
The three dimensions in the model are longitude, latitude and altitude. The top image shows effects after 40 days, the bottom after days.
A co-author was nuclear winter modelling pioneer Vladimir Alexandrov. As of , there remains ongoing speculation by friend, Andrew Revkin , of foul play relating to his work. In a regional nuclear conflict scenario where two opposing nations in the subtropics would each use 50 Hiroshima -sized nuclear weapons about 15 kiloton each on major population centers, the researchers estimated as much as five million tons of soot would be released, which would produce a cooling of several degrees over large areas of North America and Eurasia, including most of the grain-growing regions.
The cooling would last for years, and, according to the research, could be "catastrophic". These are then lifted upwards by thermal convection. As they reach the stratosphere, these nitrogen oxides are capable of catalytically breaking down the Ozone present in this part of the atmosphere. Ozone depletion would allow a much greater intensity of harmful ultraviolet radiation from the sun to reach the ground. Mills et al. Nuclear summer Edit A "nuclear summer" is a hypothesized scenario in which, after a nuclear winter caused by aerosols inserted into the atmosphere that would prevent sunlight from reaching lower levels or the surface,  has abated, a greenhouse effect then occurs due to carbon dioxide released by combustion and methane released from the decay of the organic matter and methane from dead organic matter and corpses that froze during the nuclear winter.
The nuclear detonations would release CO2 and other greenhouse gases from burning, followed by more released from decay of dead organic matter. The detonations would also insert nitrogen oxides into the stratosphere that would then deplete the ozone layer around the Earth. As the temperature rises, the amount of water in the atmosphere would increase, causing further greenhouse warming of the surface, and if it rose enough, it could cause the sublimation of methane clathrate deposits on the sea floor, releasing huge amounts of methane , a greenhouse gas, into the atmosphere, perhaps enough to trigger runaway climate change.
The high temperatures of the nuclear fireballs could destroy the ozone gas of the middle stratosphere. Ozone reaches its maximum concentration at about 25 km c.
This report is described in a report by the Defense Threat Reduction Agency as the initial study of the "nuclear winter" concept. It indicated no appreciable chance of explosion-induced climate change. A section in that book entitled "Nuclear Bombs and the Weather" states: "The dust raised in severe volcanic eruptions , such as that at Krakatoa in , is known to cause a noticeable reduction in the sunlight reaching the earth The amount of [soil or other surface] debris remaining in the atmosphere after the explosion of even the largest nuclear weapons is probably not more than about one percent or so of that raised by the Krakatoa eruption.
Further, solar radiation records reveal that none of the nuclear explosions to date has resulted in any detectable change in the direct sunlight recorded on the ground. Batten, while primarily analysing potential dust effects from surface bursts,  it notes that "in addition to the effects of the debris, extensive fires ignited by nuclear detonations might change the surface characteristics of the area and modify local weather patterns Following studies on the potential effects of NOx generated by engine heat in stratosphere flying Supersonic Transport SST airplanes in the s, in , John Hampson suggested in the journal Nature that due to the creation of atmospheric NOx by nuclear fireballs , a full-scale nuclear exchange could result in depletion of the ozone shield, possibly subjecting the earth to ultraviolet radiation for a year or more.
The authors conclude that neither the data nor their models show any correlation between the approximate Mt in historical atmospheric testing and an increase or decrease of ozone concentration. Martin describes views about potential ozone loss and therefore increases in ultraviolet light leading to the widespread destruction of crops, as advocated by Jonathan Schell in The Fate of the Earth , as highly unlikely.
Parson in the s. The story, primarily about a team of scientists hunting down mutants ,  warns of a " Fimbulwinter " caused by dust that blocked sunlight after a recent nuclear war and speculated that it may even trigger a new Ice Age. Parsons that the story "Torch" by C. Muench, et al. In general these reports arrive at similar conclusions as they are based on "the same assumptions, the same basic data", with only minor model-code differences.
They skip the modeling steps of assessing the possibility of fire and the initial fire plumes and instead start the modeling process with a "spatially uniform soot cloud" which has found its way into the atmosphere. Turco , Owen Toon , Thomas P. Ackerman, James B.
Pollack and Carl Sagan announcement of their results in "was with the explicit aim of promoting international arms control". Crutzen and John Birks began preparing for the publication of a calculation on the effects of nuclear war on stratospheric ozone, using the latest models of the time.
This darkness, they said, could exist "for as long as the fires burned", which was assumed to be many weeks, with effects such as: "The normal dynamic and temperature structure of the atmosphere would After reading a paper by N.
Bochkov and E. The use of these influential Martian dust storm models in nuclear winter research began in ,  when the Soviet spacecraft Mars 2 arrived at the red planet and observed a global dust cloud. The orbiting instruments together with the Mars 3 lander determined that temperatures on the surface of the red-planet were considerably colder than temperatures at the top of the dust cloud.
Following these observations, Golitsyn received two telegrams from astronomer Carl Sagan , in which Sagan asked Golitsyn to "explore the understanding and assessment of this phenomenon. Golitsyn felt that his model would be applicable to soot after he read a Swedish magazine dedicated to the effects of a hypothetical nuclear war between the USSR and the US.
Golitsyn presented his intent to publish this Martian derived Earth-analog model to the Andropov instigated Committee of Soviet Scientists in Defence of Peace Against the Nuclear Threat in May , an organization that Golitsyn would later be appointed a position of vice-chairman of.
Sagan had also worked on Project A in the s—s, in which he attempted to model the movement and longevity of a plume of lunar soil. Stenchikov also publishing a paper in December on the climatic consequences, although in contrast to the contemporary TTAPS paper, this paper was based on simulations with a three-dimensional global circulation model.
Richard Turco and Starley L. Thompson were both critical of the Soviet research. Turco called it "primitive" and Thompson said it used obsolete US computer models. Phillips to review the state of the science. The smoke resulting would be largely opaque to solar radiation but transparent to infrared, thus cooling the Earth by blocking sunlight, but not creating warming by enhancing the greenhouse effect.
The optical depth of the smoke can be much greater than unity. Forest fires resulting from non-urban targets could increase aerosol production further. Dust from near-surface explosions against hardened targets also contributes; each megaton-equivalent explosion could release up to five million tons of dust, but most would quickly fall out; high altitude dust is estimated at 0.
Burning of crude oil could also contribute substantially. Smoke stabilised for approximately one year. The maximum assumed extent of the combined plumes from over six hundred fires during the period of February 15 — May 30, , are available. Turco, John W. Birks, Carl Sagan, Alan Robock and Paul Crutzen — collectively stated that they expected catastrophic nuclear winter like effects with continental-sized effects of sub-freezing temperatures as a result of the Iraqis going through with their threats of igniting to pressurized oil wells that could subsequently burn for several months.
When Operation Desert Storm began in January , coinciding with the first few oil fires being lit, Dr. He also argued that he believed the net effects would be very similar to the explosion of the Indonesian volcano Tambora in , which resulted in the year being known as the " Year Without a Summer ". Sagan listed modeling outcomes that forecast effects extending to South Asia , and perhaps to the Northern Hemisphere as well.
Sagan stressed this outcome was so likely that "It should affect the war plans.
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See also: Thermal column Firestorm schematic: 1 fire, 2 updraft, 3 strong gusty winds, A pyrocumulonimbus cloud A firestorm is created as a result of the stack effect as the heat of the original fire draws in more and more of the surrounding air. This draft can be quickly increased if a low-level jet stream exists over or near the fire. As the updraft mushrooms, strong inwardly-directed gusty winds develop around the fire, supplying it with additional air. This would seem to prevent the firestorm from spreading on the wind, but the tremendous turbulence created may also cause the strong surface inflow winds to change direction erratically. Firestorms resulting from the bombardment of urban areas in the Second World War were generally confined to the areas initially seeded with incendiary devices, and the firestorm did not appreciably spread outward. This occurred with the Durango fire,  and probably with the much greater Peshtigo Fire.
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General Edit "Nuclear winter," or as it was initially termed, "nuclear twilight," began to be considered as a scientific concept in the s, after it became clear that an earlier hypothesis, that fireball generated NOx emissions would devastate the ozone layer , was losing credibility. It was within this context that the climatic effects of soot from fires became the new focus of the climatic effects of nuclear war. Once the quantity of soot is decided upon by the researchers, the climate effects of these soot clouds are then modeled. Turco in reference to a 1-dimensional computer model created to examine the "nuclear twilight" idea, this 1-D model output the finding that massive quantities of soot and smoke would remain aloft in the air for on the order of years, causing a severe planet-wide drop in temperature.