Summary of Thursday September 1

Planetary Atmospheres

• Large planets have H2, He, CH4, and NH3
• present only in small quantities on earth
• large planet's gravity holds light gases in
• large planets are cold (farther from sun) so gases move slower

Composition of Earth's Atmosphere

• oxygen on earth is from plants
• before oxygen on earth, no ozone, so uv reached surface, thus early plants in water only
• as oxygen & ozone built up, plants & animals could come on land

earth: (based on dry air)

• N2 . . . 78%
• O2 . . . 21%
• H2O . . 0 - 4%
• A . . . . 1%
• CO2 . 0.036%
  • recent change and past changes in CO2

Air Pollutants

• problems with air pollutants
• air pollutant sources: SO2, NOx, VOC, Particles (PM-10) and CO

Air Density and Air Pressure

• Change in air pressure with height

Temperature Profile

• terms: lapse rate, inversion
• layers: troposphere, stratosphere, mesosphere, thermosphere
• add 'pause' to layer to indicate top of layer
• tropopause higher over equator than over poles