Atmosphere of Earth that gas. The stratosphere defines a layer in which temperatures rise with increasing altitude. This rise in temperature is caused by the absorption of ultraviolet radiation (UV) radiation from the Sun by the ozone layer, which restricts turbulence and mixing. Although the temperature may be at the tropopause, the top of the stratosphere is much warmer, and may be near 0 °C. The stratospheric temperature profile creates very stable atmospheric conditions, so the stratosphere lacks the weather-producing air turbulence that is so prevalent in the troposphere. Consequently, the stratosphere is almost completely free of clouds and other forms of weather.
Exposing Microorganisms in the Stratosphere Exposing Microorganisms in the Stratosphere Exposing Microorganisms in the Stratosphere (E-MIST) is a NASA study to determine if a specific microorganism could survive conditions like those on the planet Mars. The study transported "Bacillus pumilus" bacteria and their spores by helium-filled balloon to the stratosphere of Earth (~31 km above sea level) and monitored the ability of the microorganisms to survive in extreme Martian-like conditions such as low pressure, dryness, cold, and ionizing radiation. A test flight of the balloon and gondola was launched from New Mexico on 24 August 2014. A second, longer flight, took place on 10 October