Even a few centimeters above the surface, however, temperatures are lower. Normally, the thin Martian atmosphere is clear and the planet's surface can be easily seen. Occasionally, there are clouds. The white or blue-white clouds are composed of H 2 O ice crystals or, more commonly, carbon dioxide ice crystals. These can be seen around the summits of Mars' huge, extinct volcanoes, along the sunrise limb of the planet or in the canyons.
Yellowish clouds are the result of fine grains of Martian desert dust being blown into the air.
Occasionally, especially when warm summers come to the Southern hemisphere, giant dust storms spread to cover most of the planet for weeks in billowing clouds that are several miles high. Because the Martian atmosphere is so thin, however, you would feel much less pressure from the wind than if you stood in a similar speed wind on earth. Light frosts do occur on Mars and light snows may occasionally fall, but most of the build up in the Martian polar caps during the winter months is due to direct condensation of H2O and carbon dioxide out of the atmosphere. The project, developed at the University of Chicago, also suggests the teacher may want to have encyclopedia and other book resources available for students to read about the Dust Bowl which took place in the Great Plains region of the United States in the 1930s. Objective Students will research temperature and wind data locally, nationally and internationally and compare these to conditions on Mars, and draw conclusions about differences and causes.