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.

Scintillation - The apparent twinkling of a star due to its light passing through regions of differing air densities in the atmosphere. This results in the light being refracted and scattered before it reaches the viewer.

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.

Stratus - A low, generally gray cloud layer with a fairly uniform base. Stratus clouds have the appearance of fog that doesn't reach the ground. These clouds tend to be associated with either no precipitation or light precipitation such as drizzle.

Greenhouse effect - The term that describes how the Earth receives solar radiation and how it is essentially trapped in the Earth's atmosphere. The incoming solar radiation is absorbed at the surface and then radiates back up to space in the form of infrared radiation. However, the greenhouse gases in the atmosphere absorb some of this outgoing radiation and then re-radiate it back down to the surface. The higher the concentration of greenhouse gases, the more magnified this effect becomes.

Deposition - The process where water turns directly from vapor to ice, without first becoming liquid. A common instance of deposition is when frost forms on the grass during cold mornings.

Sub-vortices - Small areas of intense rotation located within a type of tornado called a multi-vortex tornado. These spinning whirls can be thought of as individual tornadoes that are mixed within the main tornado. These are also sometimes referred to as suction vortices and the winds within them can be 100 mph stronger than the main body of the tornado. These can explain why the damage path in a tornado can vary greatly.