Hadley cell - A thermally driven air circulation in tropical and subtropical latitudes of both hemispheres. The Hadley cell resembles a huge convective cell with rising air near the equator and sinking air in the subtropical latitudes. This concept was first introduced by George Hadley in 1735.

Katabatic wind - A downslope wind that flows from high elevations down to the valleys or plains below. Katabatic winds are driven by the fact that cold air is heavier and more dense than relatively warmer air. When cold air pools in higher elevations and becomes significantly colder than the air below, the heavier air accelerates down into the lower elevations. Katabatic winds are most common near the elevated ice sheets of Antarctica and Greenland and can exceed hurricane force at times.

Loaded Gun (Sounding) - A description of the state of the atmosphere that is characterized by extreme instability. Loaded gun soundings contain a stable layer, called a cap, that must be broken through in order for the instability to be unleashed. If the cap is overcome, rapid development of strong to severe thunderstorms can be expected.

Transpiration - The process by which water escapes plants into the air and turns into water vapor. The rate at which plants lose water to the air increases as the temperature increases. Corn plants transpire at a rate higher than most plants. This means that corn needs more moisture to survive compared to most plant life.

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!

Squall - A sudden increase in wind speed, usually associated with lines of convective thunderstorms. A squall can also be used when describing quick-hitting, heavy lake-effect snow bands.

Freezing Drizzle - A drizzle that falls as a liquid but then freezes into a light glaze or rime upon contact with the cold ground. Freezing drizzle is different than freezing rain because it accumulates at a much slower rate. Freezing drizzle tends to be localized and not widespread, which makes it more difficult to predict.