Atmospheres An atmosphere can change a planet's surface. First look at structure of generic atmosphere. Atmospheric structure Atmosphere changes with height in both temperature and pressure. Balance between gravity and gas pressure again .
Gravity pulls atmosphere closer, gas pressure tries to expand it outward.
Higher you go, less atmosphere there is above you and less weight to push down so pressure decreases. Most visual light reaches the ground, passing through the atmosphere more or less unabsorbed but some scattered. The rotation rate of the planet, which determines how long the sunlight will hit any one patch of the planet. Generally re-radiated in the infrared wavelength region. Scattered blue light reaches our eyes from all directions so sky is blue.