Fulgurites - Fulgurites are glassy, root-like tubes formed when a lightning stroke terminates in a dry sandy soil. When the lightning bolt strikes the sand, it heats it to around 50,000 degrees Fahrenheit. This melts the sand and gives it a dark glasslike appearance. The diameter of a fulgurite is typically between 1 and 2 inches, while the length can reach up to 5 feet.

Thunderstorm - A local storm that spawns from a cumulonimbus cloud and is accompanied by lightning and thunder. The atmospheric conditions needed to produce a thunderstorm are warm and moist conditions in the low levels. It is estimated that around 1,800 thunderstorms are occurring on Earth at any given moment.

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.

Winter Weather Advisory - Issued by the National Weather Service for alerting the public to conditions which will moderately hamper travel. Winter weather advisories can be issued for anticipated freezing rain, sleet, or snow that is expected to accumulate. Winter weather advisories can also be issued due to blowing snow as well.

Blue Jet - An upper-level atmospheric electrical discharge, usually blue or bluish-white in color, that occur high above thunderstorms. Similar to sprites. This phenomenon is believed to connect the tops of thunderstorms with the ionosphere.

Wedge tornado - A term used by observers that indicates that the tornado looks wider than the distance from the ground to the cloud base. Essentially, it is a slang term to describe a very wide tornado. Rather than having the typical funnel shape, a wedge tornado often appears as a large, flat cloud reaching the ground. These are often-times multi-vortex tornadoes, where large amounts of dirt and debris can conceal the individual funnels.

Millibar - A millibar is a measure of atmospheric pressure taken by a barometer. The standard pressure measured at the surface is 1,013 millibars. Other units that are used for pressure measurements are inches of mercury and pascals. The lowest pressure readings that have occurred at the surface have been measured underneath intense hurricanes.