Derecho - A widespread and usually fast-moving complex of thunderstorms that produce damaging straight-line winds. These systems are long lived, as the swath of wind damage associated with them extends for hundreds of miles. Wind gusts can range from 60 to over 100 mph in a derecho.

Equinox - Time of year when day and night are nearly equal in length. The equinoxes signal a transitional time of year. In the northern hemisphere, the autumnal equinox is the transition season that leads up to winter. Conversely, the vernal equinox is the transition season of spring that leads to summer. On the equator, the sun can be seen directly overhead at noon on the day of an equinox.

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.

Tropopause - Zone of the atmosphere that marks the transition between the troposphere below and the stratosphere above. The tropopause is the top of the troposphere. 75 percent of the mass of the atmosphere is located below the tropopause. The height of the tropopause varies between 4 to 12 miles.

Fog - Typically fog is composed of water droplets suspended in the air near the Earth's surface. When bitter cold temperatures are present, fog is composed of ice crystals instead of water droplets, and is called ice fog. Both types of fog reduce visibility at the surface.

Lilapsophobia - This is the fear of tornadoes/hurricanes. People that have lived through the occurrence of a severe hurricane or tornado are most susceptible to this phobia.

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.