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The surface of Mars is a desert. The most important property of the soil for meteorology considerations is its thermal inertia. This is related to the ability of the soil to respond to a given energy input (such as heating by the sun). Martian soil has a very low thermal inertia, which means that a given energy input leads to relatively large surface temperature changes. Except during winter, the Martian surface experiences temperature swings each day as large as 100K in response to solar heating. This in turn forces large swings in atmospheric temperature since the surface pressure is so low. On Earth, the greatest differences in thermal inertia exist between land and sea. This is because on land, heat can only be drawn away from the surface downwards by conduction. In the sea, vertical motions act to mix heat downwards, preventing the surface temperature from rising too much in response to a given heat input. This is why during the day, the oceans are cooler than the land, while at night the land can cool down more than the ocean. Sea breezes are a consequence of this |
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| On Mars, there are no
seas. However, large differences in surface properties such as the
thermal inertia discussed above can exist, and these can force
circulations akin to sea breezes each day. During the day, air flows
from the colder region to the hotter region (equivalent to onshore
flow), and vice versa at night (equivalent to offshore flow). An important consequence of the dry desert surface (and the cold conditions) is that heating the surface does not result in much evaporation of water. On Earth, the evaporation of water and its subsequent recondensation at higher levels plays a major role in the atmospheric circulation and in the development of storms and hurricanes. On Mars, this effect is very small indeed. |
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Responsible NASA Official: Robert
Haberle
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Last Updated: 08/29/04
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Designed by: James
Schilling
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