Atmosphere - escape speed gas molecules can escape from planet if travelling fast enough Air molecules are always in motion speed depends on

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Atmosphere From space Earth looks blue: from : 1. scattered light in atmosphere 2. reflected light from oceans Light scattering: molecules and dust in atmosphere scatter light which colors scatter best depends on particle size in our atmosphere, size is right to scatter blue best   sky is blue setting sun looks red Atmosphere Composition   78  % Nitrogen (N 2 ) from decay of biological stuff and volcanic eruptions 21  % oxygen (O 2 ) from photosynthesis in plants (CO 2  -> O 2 ) 1 % everything  else   if no life on Earth => very different atmosphere Ancient atmosphere had more hydrogen (which escaped), methane and amonia Composition depends on: 1. original formation of planet - what gasses were trapped 2. chemical processes (including life) 3. escape speeds of different molecules
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Unformatted text preview: escape speed: gas molecules can escape from planet if travelling fast enough Air molecules are always in motion speed depends on temperature and mass of molecules hotter => faster => easier to escape lighter => faster => easier to escape If a planet's atmosphere is hot enough, light elements will escape Earth is hot enough for hydrogen and helium to escape Atmosphere and temperature atmosphere absorbs energy from sunlight X-rays and ultraviolet radiation are absorbed at different altitudes average surface temperature is about 300 K if no atmosphere, would be about 270 K (below freezing) This temperature difference comes from the "greenhouse effect" atmosphere traps heat near Earth's surface...
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This note was uploaded on 03/09/2012 for the course AST 1002 taught by Professor Emilyhoward during the Spring '10 term at Broward College.

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Atmosphere - escape speed gas molecules can escape from planet if travelling fast enough Air molecules are always in motion speed depends on

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