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The stratosphere is a layer of the earth’s atmosphere above the troposphere and below the mesosphere. It is heated by the direct absorption of ultraviolet radiation by the sun, causing temperatures to increase with altitude. The height of the stratosphere varies with latitude and is often used as a euphemism for “really high up.” The lack of vertical diffusion in the stratosphere eliminates turbulence, making it a popular cruising altitude for commercial airliners and military aircraft. Gliders rely on thermal plumes that terminate at the base of the stratosphere, but this limit can be overcome by exploiting the ridge rise. The first man-made object to reach the stratosphere was a shell fired from the Paris Gun during World War I.
The stratosphere is a region of the earth’s atmosphere, above the troposphere and below the mesosphere. Unlike the underlying troposphere, which gets cooler with increasing altitude, temperatures in the stratosphere increase with altitude, because the upper stratosphere is heated by the direct absorption of ultraviolet radiation by our Sun.
The point where the stratosphere begins, the tropopause, is measured from where this temperature inversion begins to occur. The height of the stratosphere varies according to the latitude it is speaking about: at moderate latitudes, the stratosphere begins about 10 km (6 mi) from the surface and ends at 50 km (31 mi), at the poles it begins only 8 km (8 mi) 5 miles) of altitude. This is because the ground at the poles is so cold that it doesn’t take long to produce higher temperatures and so the stratosphere starts earlier.
The word “stratosphere” or “stratospheric” is often used as a euphemism for “really high up.” Compared to all the divisions for the earth’s atmosphere – troposphere, stratosphere, mesosphere, thermosphere and exosphere, by increasing altitude – the stratosphere isn’t quite that high, but from our point of view here on earth, it’s more or less high as is any typical person. The cruising altitude of commercial airliners is about 10 km (6 mi), which puts them above severe weather. Unlike the lower tropopause, where turbulence-causing convection dominates, the stratosphere is in thermal equilibrium, like a layer cake, since horizontal diffusion is therefore much faster than vertical diffusion. The lack of vertical diffusion therefore eliminates the cause of the turbulence. Occasionally, ascent from the tropopause produces turbulence in the lower reaches of the stratosphere, where aircraft fly, which is responsible for any turbulence during the cruise phase of flight.
The lower stratosphere is the maximum possible altitude at which a glider can fly, because gliders rely on thermal plumes that rise above the ground and terminate at the base of the stratosphere. However, these limits can be overcome by exploiting the ridge rise, an atmospheric thermal phenomenon that occurs only at the edge of mountain ranges.
The first man-made object to reach the stratosphere was a shell fired from the Paris Gun, a 20-metre (67-foot) supergun built by the Germans during World War I. Its aim was to fire on Paris from within German borders. This gun could fire a 120 kg shell with 7 kg (15 lb) of explosive at a range of 131 km (81 mi) and an altitude of 40 km (25 mi). Today, military fighter jets and bombers regularly cruise the lower-middle stratosphere.
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