Hydrometeor - Any product of condensation or deposition of atmospheric water vapor, whether formed in the free atmosphere or at the earth's surface. Sea spray blown into the air is also composed of hydrometeors. Raindrops, snowflakes, and all other types of precipitation qualify as hydrometeors.

Planetary Boundary Layer - Also known as the Atmospheric Boundary Layer, it is the lowest part of the atmosphere and its behavior is directly influenced by its contact with the surface. The depth of the planetary boundary layer changes from day to night. During the day, the sun heats up the surface resulting in rising air currents that raise the height of the boundary layer. At night, the height of the boundary layer falls very close to the surface.

Anomalous Propagation - Often abbreviated as AP. It is a false reflectivity echo on the radar display. Instead of being caused by precipitation, these false echos occur when the radar beam is refracted back down towards the surface, thereby producing ground clutter. Other examples of AP can occur when the radar beam bounces off of insects, birds, or other airborne wildlife. High terrain areas, such as mountain ranges can also cause AP.

Lake Breeze/Sea Breeze - A sea or lake breeze develops due to temperature differences between the surface of the sea and land. Because water temperatures over a large body of water are more constant than land temperatures, a density gradient develops when the land heats up during the afternoon, thereby inducing a cool breeze that blows from the sea over the land. The opposite of a sea breeze is a land breeze. This occurs during calm nights when the land cools and becomes colder than the sea surface temperatures. A land breeze blows from the land out to sea.

Polar Vortex - The polar vortex is an area of low pressure that coincides with the pool of arctic air that encircles the North or South Pole. Each fall, the polar vortex begins to form due to decreasing daylight near the poles. By mid-winter it becomes more influential to the weather patterns in the mid-latitudes.

Chromosphere - In relation to the sun, the chromosphere is the second of the 3 main layers of the sun's atmosphere. The chromosphere sits above the photosphere and below the solar transition region. The chromosphere is composed mainly of hydrogen gas that is hotter than 6000 degrees kelvin or 10,300 degrees on the fahrenheit scale.

La Nina - La Nina is the cool phase of the El Nino-Southern Oscillation cycle. During a La Nina event, the east-central Equatorial Pacific Ocean becomes abnormally cool due to stronger than normal trade winds. La Nina events are a boon to the Peruvian fishing industry due to the nutrient rich waters that develop off the coast of western South America. Global weather patterns can also be influenced by the presence of a La Nina.