parts of atmosphere - 4 regions
- troposphere - where people live, goes to about 12 km
- stratosphere - reaches 50 km
- mesosphere - reaches 85 km
- thermosphere - past mesosphere
- temperature change opposite in successive region
- pressure change remains constant (decreases as elevation increases)
atmospheric composition - made up of mostly nitrogen, oxygen
- nitrogen = 78%
- oxygen = 21%
- argon, carbon dioxide, water vapor = next most commonly found gases
- oxygen reacts more than nitrogen (triple bond)
- photodissociation - photons from the sun breaking chemical bonds
- O2 + energy >> 2O
- mostly dissociated at very high elevations
- photoionization - loss of electron due to molecule absorbing radiation
- ozone (O3) forms from photodissociated oxygen and oxygen molecules
- most ozone found in stratosphere
- chlorofluorocarbons (CFC) - depletes the ozone layer
- harmless in lower atmosphere
- reaches higher atmosphere >> more radiation >> more photodissociation
- chloride w/ oxygen forms chlorine monoxide
troposphere composition - like atmosphere, mostly nitrogen/oxygen
- acid rain - due to nitrogen oxides in air
- NOx from fossil fuel burning
- kills animals, corrodes metals/stone
- carbon monoxide - along w/ cyanide, bonds to hemoglobin better than oxygen
- photochemical smog - stagnant air mass due to nitric oxide
- ozone acts as pollutant in lower atmosphere
- carbon dioxide/methane - contributes to greenhouse effect