Astronomers solve temperature mystery of planetary atmospheres

Earth Tropopause
The Sun is just below the horizon in this photo and creates an orange-red glow above Earth’s surface, which is the troposphere, or lowest layer of the atmosphere. The tropopause is the brown line along the upper edge of the troposphere. Above both are the stratosphere, higher atmospheric layers, and the blackness of space.

University of Washington (UW) researchers Tyler Robinson and David Catling have found an atmospheric peculiarity Earth shares with Jupiter, Saturn, Uranus, and Neptune is likely common to billions of planets, and knowing that may help in the search of potentially habitable worlds. Earth and other solar system worlds have a tropopause, or level where the atmosphere stops cooling and begins heating up, at or near 0.1 bars. Using an analytic model, Robinson and Catling show that at high altitudes atmospheres become transparent to thermal radiation due to the low pressure. Above the level where the pressure is about 0.1 bar, the absorption of visible, or ultraviolet, light causes the atmospheres of the giant planets — and Earth and Titan — to grow warmer as altitude increases.

Read more at Astronomy Magazine