Topic 4 Flashcards
Atmospheric Compositions
atmosphere contains?
Gases (permanent and variable)
Water droplets (clouds and precipitation)
Microscopic solid particles (aerosols)
permanent gases
nitrogen, oxygen, and argon
variable gases
water vapor
trace gases
carbon monoxide, methane ozone, CFCs, etc
Gases form a constant proportion of the atmosphere, and have long residence times (thousands to millions of years).
Permanent gases
Gases vary in atmospheric concentration in both time and space.
variable gases
Extremely important variable gas with short residence time (~10 years).
water vapor
Invisible gaseous phase of water.
water vapor
Atmospheric concentration highest near ocean surface in tropics
(~4%).
Atmospheric concentration lowest in deserts and at high altitudes
(near 0%)
An important greenhouse gas with concentration of 0.0386% (386ppm) and residence time of 150 years.
Carbon dioxide
sources of carbon dioxide
Sources
- Plant and animal respiration
- Volcanoes
- Organic decay
- Combustion
carbon dioxide sink
Sinks
- Photosynthesis (plants)
- Oceans
A beneficial and harmful variable gas.
ozone
Ozone concentrations in the stratosphere (~10-30 miles above sea level) are?
relatively high
Ozone concentration near earth’s surface is usually _____, but can increase to 0.15 ppm through chemical reactions in polluted air (irritant).
near zero
A variable gas with residence time of ~10 years that has high potential for greenhouse warming.
methane
Methane Sources
Sources
1. Rice cultivation, wetlands
2. Mining
3. Biomass burning
4. Fossil fuel extraction
5. Animal digestion
Methane Sinks
- Atmospheric chemical reactions
Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
Aerosols
Typical concentration of aerosols
= 17,000/in3
Typical diameter of aerosols
= 10 microns (0.00001 meter)
Typical life span of aerosols =
days to weeks.
Mostly from natural sources.
aerosols
Aerosols primary sinks
Primary sinks include dry and wet deposition.
Act as cloud condensation nuclei
aerosols
