Greenhouse Effect
Sunlight passes through the atmosphere and warms the Earth's surface. Greenhouse gases (GHGs), such
as water vapor, carbon dioxide, and other gases, trap some of the Sun's energy as it is being
radiated back into space, causing the atmosphere to warm (see diagram).
1 More accurately, molecules
of GHG are continuously absorbing and releasing heat, indirectly warming the surrounding atmosphere
and the Earth’s surface.
The amount of heat from the “greenhouse effect” would be relatively stable as long as the mixture of
GHGs in the atmosphere remains relatively stable, conditions at the Earth’s surface remain relatively
constant, and the amount of energy coming to the Earth from the Sun remains stable.
Right now, the natural greenhouse effect is maintaining an average annual temperature of about
59°F at the surface of the Earth. Without the greenhouse effect, the average annual temperature
at the Earth's surface would be around 0°F!
2
References:
- Diagram of Greenhouse Effect, Wes Peck, EERC
-
www.physicalgeography.net/fundamentals/7h.html (accessed August 2006).