Anatomy of Mars Help (page 2)

By — McGraw-Hill Professional
Updated on Sep 16, 2011

Atmosphere And Weather

Mars has oxygen, but almost all of it is bound up with elements in the surface and with carbon in the atmosphere. The result is a rusty world, with an atmosphere consisting almost entirely of carbon dioxide (CO 2 ). The barometric pressure at the surface of Mars is less than 1 percent of the pressure on Earth. Were it not for the fact that CO 2 is a heavy gas, the atmosphere of Mars would be even thinner than this.

Despite the thin air on Mars, weather occurs, and it can be extreme. Winds aloft can reach speeds of around 400 kilometers per hour (250 miles per hour); near the surface, they commonly rise to 120 kilometers per hour (75 miles per hour). It would be a mistake to say that such winds are of “hurricane force” because the thin air on Mars produces far less wind pressure for a given wind speed than the air on Earth. However, dust particles from the surface are picked up and travel right along with the wind, blowing high up into the atmosphere, where they at times shroud the planet completely. During these massive dust storms, which can be accompanied by lightning, the surface features of the planet practically disappear. As seen from the surface, such a storm would produce a dark red sky, obscuring the sun and casting an evil gloom over the landscape.

One of these planetwide dust storms was indirectly responsible for the discovery of the four largest Martian volcanoes. These include Olympus Mons (already mentioned as the largest mountain on the planet), Ascraeus Mons, Pavonis Mons , and Arsia Mons . As the storm abated, the dust gradually settled. The peaks of the volcanoes were seen first; more and more of them appeared as the Martian sky regained its characteristic clarity.

High clouds, similar to cirrostratus and cirrus clouds on Earth, are sometimes observed on Mars. In addition, Olympus Mons is occasionally shrouded in a thin veil of cloud, in much the same way as high mountains are cloud-covered on Earth. These Martian clouds are far less substantial than their Earthly counterparts, and scientists doubt that they produce much, if any, precipitation. However, they do produce a sort of fog at the top of Olympus Mons. Standing inside the caldera of this monstrous mountain on a foggy morning, you might for a moment imagine yourself in the Namib Desert on the southwestern African coast.

Practice problems of this concept can be found at: Mars Practice Problems

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