St. Elmo's fire - A bright electric discharge that is projected from objects when they are in a strong electric field, such as occurs during a thunderstorm. This discharge can cause a ship's mast or airplane wings to have a greenish or bluish glow.

Rawinsonde - An instrument attached to a weather balloon that measures atmospheric pressure, temperature, humidity, and wind speed/direction at different layers of the atmosphere. As the instrument rises through the atmosphere, the data is sent via radio waves to a receiver on the ground. Rawinsondes are launched all over the world at specified times. The data from these launches is used in initializing the numerous forecast models.

Shelf Cloud - Also known as a roll cloud. A low, horizontal, sometimes wedge-shaped cloud formation associated with the leading edge of a thunderstorm's outflow winds or gust front. Shelf clouds normally stretch across the entire horizon as an organized line of storms approaches. When a shelf cloud is observed, prepare for a quick increase in winds. A severe line of storms can produce shelf clouds that indicate incoming straight-line winds of over 60 mph.

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.

Anabatic - refers to a rising wind flow, oftentimes climbing up a hill or mountainside. Anabatic winds are driven by localized heating at the surface, which creates a rising current of air due to the lower density that warmer air has.

Synoptic Scale - In meteorology this refers to the study of large scale systems that develop in the atmosphere. Major cyclones and their associated fronts are a commonly studied feature in synoptic meteorology. In order to be on the synoptic scale, a system must stretch across a distance of at least 600 miles.

Avalanche - A large mass of rapidly moving snow down a steep mountain slope. Most avalanches are triggered by the people that become victim to them. On average, around 150 people are killed by avalanches each year.