Quote:Actually CO2 absorbs heat and begins to vibrate. The CO2 molecules will eventually emit the energy and stop vibrating. What you described sounds like CO2 is reflecting heat like a mirror reflects sun light, but the CO2 is actually absorbing heat and keeping it within the atmosphere. When the heat is released it is usually absorbed by another greenhouse gas.
If this picture of heat quanta being bounced around between greenhouse gas molecules were correct, the system would quickly become saturated, and the earth would settle down to a nice cool 3K.
What the molecules "absorb" are photons in the infrared region (where the earth's blackbody peak is). You are right that this excites molecular vibrational modes though. The photons are redradiated isotropically, some back to earth, some out to space.
So the analogy of a mirror that you used is actually a reasonable one, with the reflectivity a function of photon frequency.
Those radiated back to earth heat it in the same way as solar photons, by exciting atomic and molecular vibrational modes and contributing to their kinetic energies.
Galileo was a man of science oppressed by the irrational and superstitious. Today, he is used by the irrational and superstitious who claim they are being oppressed by science - Mark Crislip
