Acid Rain - Rain that has a pH lower than 5. Normally rain has a pH around 5.6. Acid rain occurs due to the presence of sulfuric and nitric acid. Coal burning power plants are the largest contributor to the formation of acid rain, which is toxic to aquatic environments.

Mesoscale - Mesoscale is the study of meteorology concerned with small scale weather systems that are from 6 to 60 miles in diameter. The discipline of mesoscale meteorology is focused on phenomenon such as thunderstorms, land or sea breezes, and downslope wind storms.

Knots - The unit meteorologists use to measure winds speeds. Knots are the common unit pilots and sailors use when gauging wind speeds. A knot is based on nautical miles rather than statute miles. A wind speed of 1 knot is equal to 1.15 mph.

Cap Cloud - A stationary stratiform cloud that forms directly above an isolated mountain peak. This type of cloud develops when moist air pushes against the mountain and is forced upward. As the air rises it eventually cools enough for the water vapor to condense and form a cloud.

Advection - The transfer of an atmospheric property by wind. The most common entities that meteorologists look at when diagnosing areas of advection are temperature and moisture.

Microscale - Microscale meteorology is the study of small and/or short-lived atmospheric phenomenon. This study of small-scale weather systems includes tornadoes, rainbows, and thunderstorm updrafts and downdrafts.

Sublimation - Any process where a solid turns directly into a gas. In meteorology, this term is used to describe the process by which ice turns to water vapor. This process can be seen when observing the behavior of dry ice. Dry ice is actually frozen carbon dioxide that turns to carbon dioxide gas when it breaks down.