Aurora - Luminous phenomena that appear in the form of arcs, bands, draperies, or curtains in the high atmosphere over high latitudes. Auroras are related to magnetic storms and the influx of charged particles from the Sun. The phenomena are called aurora borealis in the Northern Hemisphere and aurora australis in the Southern Hemisphere.

Cloud - Any visible mass of water droplets, ice crystals, or a mix of both that become suspended in the atmosphere. Fog is a cloud that forms at the ground, while cirrus clouds oftentimes form at around 40,000 feet.

Tropic of Capricorn - The Tropic of Capricorn is an imaginary line of latitude going around the Earth at approximately 23.5 degrees south of the equator. It is the southernmost point on Earth where the sun's rays can be directly overhead. On the day of the Northern Hemisphere's winter solstice, the sun will be directly overhead at noon here.

Clear Slot - In respect to severe thunderstorms, a clear slot is a local region of clearing skies or reduced cloud cover. This oftentimes indicates that there is an intrusion of drier air, oftentimes noted by a bright area with higher cloud bases on the west or southwest side of a wall cloud. A clear slot is believed to be a visual indication of a rear flank downdraft

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.

Eddy viscosity - The turbulent transfer of momentum by eddies giving rise to internal fluid friction. Eddy viscosity is an important concept in turbulence theory.

Arctic Front - The semi-permanent, semi-continuous boundary that separates the deep, cold arctic air from the shallower, less frigid polar air of the northern latitudes. Major shifts in the polar jet stream can drive arctic fronts southward into the mid-latitudes during the winter season.