9.3 greenhouse effect

Solar radiation

Not all incoming solar radiation reaches earths surface

-most is absorbed and remitted into all directions through GHG & clouds → warm earths surface & lower atm

-lower albedo surfaces → absorb & release radiation (warmth)

-higher albedo surfaces → reflect sunlight to space/GHG that absorb it

Greenhouse effect & how

Gases in earths atm trap heat from the sun & radiate it back down to earth

How:

-UV strike earths surface → heating it

-earths surface releases infrared radiation

-GHG absorb infrared radiation & radiate it both out into space & back to earth

-portion coming back to earth is the “greenhouse effect”

Greenhouse gases & sources

Most important:

CO2: FF combination, decomp, deforestation

Methane: natural gas, animal ag., anaerobic decomp.

Nitrous: ag soils in overwatered/ over fertilized soil

CFCs/HCFCs/HFCs: refrigerants, blowing agents in aerosol products

Water vapor: evaporation & transpiration from plants

Global warming potential (GWP)

Measure of how much a given molecule of gas can contribute to the warming of the atmosphere over 100 year period

2 factors:

1) residence time: how long molecule stays in atm

2) infrared absorption: how well gas absorbs & radiates infrared radiation