Thermosphere - The atmospheric shell extending from the top of the mesosphere to outer space. It is a region of more or less steadily increasing temperature with height, starting at around 50 miles above the surface. This layer is around 320 miles thick and temperatures in this layer can reach 4,500 F. The International Space Station orbits the Earth in this region of the atmosphere!

Anticyclone - Another word for a high pressure system. Anticyclones occur when air piles up aloft due to convergent upper level wind flow. This raises the pressure readings at the surface, thereby creating a surface high pressure system.

Aerosols - Tiny liquid or solid particles that become suspended in the atmosphere. Some sources for aerosols are volcanoes, wild fires, desert wind storms, and the burning of fossil fuels.

Dust Bowl - An extended period of exceptional drought that affected the Great Plains of North America during the 1930s. Agricultural activities were crippled during this epic drought. Heat waves and occasional dust storms were fairly common during the dust bowl years. On some occasions, the dust storms in the Plains made it all the way to the east coast.

Doldrums - An east-west belt of light and variable surface winds where the trade winds of the two hemispheres converge. This region is located in a belt just north and south of the equator. Sailers dubbed this area as the doldrums because the lack of wind would mean their ships would stay idle for weeks at a time.

Cirrocumulus clouds - These high clouds are noted by small rounded white puffs composed of ice crystals. When the sky is covered by these clouds the sky can look like the scales of a fish, and is called a mackerel sky. These clouds are common during the cold season, and often indicate fair but chilly weather conditions.

Valley Breeze - A breeze that flows up a mountainside during the day. This upsloping breeze occurs due to the fact that the valley walls warm up faster than the higher terrain in the mountains. This makes the air in the valleys lighter than the air along the higher terrain of the mountains, making the air near the valley buoyant. The result is the upward breeze along the mountainsides during the day.