ASTR 3 Lecture Notes - Lecture 8: Solar Wind, Calcite, Aurora
28 Aug 2016
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Document Summary
A layer of gas that surrounds a planet (usually very thin) Venus has a thicker atmosphere, 100x surface pressure than earth. Mars" atmosphere is 100x thinner than earth"s. Earth"s atmosphere: 10 km thick, consists mostly of nitrogen and oxygen. Effects of atmospheres: they create pressure that determines whether liquid water can exist on surface, they absorb and scatter light. !1: they create wind, weather, and climate, they interact with the solar wind to create a magnetosphere, they can make planetary surfaces warmer through the greenhouse effect. The surface absorbs visible light and emits thermal radiation in infrared. Some visible light is re ected by clouds, haze, and the surface back into space. Greenhouse gases absorb and reemit infrared radiation, thereby heating the lower atmosphere: planetary temperature. A planet"s surface temperature is determined by the balance between the energy from sunlight it absorbs and the energy of outgoing thermal radiation. How much we absorb vs how much we give off.
