Exploratour - The Atmosphere of Mars
Warm and Cold
Warm and cold fronts may be more extreme on Mars than on the Earth because of the greenhouse effect. The greenhouse effect helps a planet maintain even temperatures from day to night. (Without the greenhouse effect, and an atmosphere, temperatures can go from 50 degrees to -50 degrees as they do on the Moon).
As shown in the diagram, certain molecules of air (greenhouse gases), such as water and carbon dioxide, serve as a trap of energy by absorbing and re-emitting energy in different directions from that in which the energy came. These molecules typically re-emit energy back into the atmosphere instead of out into space. Thus a photon of energy may enter the atmosphere from outside, but may be held inside the atmosphere for a long time, somewhat like a pinball in a pinball machine. Thus molecules can keep an atmosphere warm long after the Sun has gone away.
When the atmosphere is thin, the way the atmosphere of Mars is, the greenhouse effect is reduced. On the other hand, carbon dioxide is a powerful greenhouse gas, so perhaps the greenhouse effect is increased on Mars. More information from the atmosphere of Mars would help scientists learn more about how the greenhouse effect influences the weather of Mars.