Doppler Effect - The shift in frequency that occurs when an object goes from moving towards an observer to away from an observer. Everyone has heard this when a police car drives by. As the police car is approaching, the siren will have a high pitch. Then when the police car begins moving away from you the pitch of the siren lowers. This effect is what weather radars use to calculate velocity.

Mammatus Clouds - Cloud cover that has numerous rounded, smooth, sack-like protrusions hanging from the underside. Mammatus clouds are most commonly found in an anvil of a thunderstorm. Mammatus clouds can accompany severe thunderstorms, but they also occur often with non-severe thunderstorm activity.

El Nino - An anomalous warming of ocean waters in the east central equatorial Pacific. El Nino events occur every two to seven years and have local as well as global impacts. Nutrient deficient waters cripple the fishing industry off the coast of western South America during El Ninos, while global weather patterns can be significantly altered due to the presence of an El Nino.

Haze - Haze can be composed of fine dust, smoke, salt particles, or atmospheric pollutants. These particles become coated with water droplets giving them an even larger bearing on sky conditions and visibility. Haze gives the sky a milky tone due to the veil it puts between us and the sun.

Cyclogenesis - The formation or intensification of a low pressure system or cyclone. The term bombogenesis refers to cyclones that undergo extremely rapid intensification.

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!

Pyranometer - An instrument that is used to measure the sun's energy, know as solar radiation. It was invented in 1893 by a Swedish meteorologist named Anders Knutsson Angstrom. This was the first instrument that could measure both direct and indirect solar radiation.