The atmosphere of Mars is much thinner than the atmosphere surrounding Earth. It consists chiefly of carbon dioxide, with small amounts of nitrogen, argon, oxygen, carbon monoxide, neon, krypton, and xenon. The planet's atmosphere also contains extremely small traces of water vapor. The atmospheric pressure (force exerted by the weight of gasses) on Mars is less than 0.15 pound per square inch (0.01 kilogram per square centimeter). It is about one-hundredth the atmospheric pressure on Earth.
Three general types of clouds can be seen in the atmosphere. Pink clouds of dust often cover large areas of the planet. Thin blue clouds are made up of ice crystals. Thicker white clouds, consist of water vapor, occasionally move across the planet.
The force of gravity on Mars is about three-eighths as strong as the force of gravity on Earth. The reduction of gravitation force is caused by the smaller mass of Mars; the mass of Mars is about a tenth of the mass of Earth. A 100-pound object on Earth would weight about 38 pounds on Mars.
The seasons last about twice as long as those on Earth because Mars takes almost twice as long to make one revolution around the sun as the Earth does. Temperatures on Mars are lower than those on Earth because Mars is farther away from the sun. During winter, night temperature can drop as low as -191 degrees F, or -124 degrees C. In summer, temperature during the day may rise as high as -24 degrees F, or -31 degrees C.