Module 1 : Atmospheric Composition and Principles of Contaminant Behavior

Lecture 3 : The Greenhouse Effect on Earth

 

Earth's atmosphere is slightly warmer than what it should be due to direct solar heating because of a mild case of greenhouse effect…

  • The ground is heated by visible and (some) infrared light from the Sun.
  • The heated surface emits infrared light.
  • The majority of Earth's atmosphere (N2 and O2) are not good greenhouse gas.
  • The small amount of greenhouse gases (H2O, CO2) traps (absorb and re-emit) the infrared radiation, increasing the temperature of the atmosphere…

 

 

 

Greenhouse Gases

  • The primary components of Earth's atmosphere, N2 and O2 do not have absorption in the IR wavelength range, therefore, do not have a significant role in setting the surface temperature of the planet…
  • Greenhouse gas are efficient in absorbing IR light … The most important greenhouse gases are:

– H2O – Water vapor.

– CO2 – Carbon dioxide

– CH4 – methane

The most abundant greenhouse gas in Earth's atmosphere is water vapor. Most of the greenhouse heating of Earth's atmosphere is due to Water vapor absorption of IR radiation emitted by Earth, and then transferring the energy to the surrounding air molecule

The Atmosphere of Earth

The atmosphere of Earth contains primarily N2 (77%) and O2 (21%).

  • What happened to all the CO2 ?
  • Where did all the O2 come from?

Atmospheres of the Terrestrial Worlds