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.

GFS (Global Forecast System) - One of the American operational forecast models run at the National Centers for Environmental Prediction. GFS stands for Global Forecast System. The GFS model is run 4 times a day and it covers the entire globe. GFS forecast output can extend up to 384 hours from when it is run.

Evapotranspiration - The sum of evaporation in which water is transferred from the land to the atmosphere. This includes moisture that evaporates from the soil and other moist surfaces, as well as moisture that is taken from plants due to transpiration.

Pluie - This is the french word for rain. To say, "it is raining today" one would say, "Il pleut aujourd'hui."

Coriolis force - An apparent force that is a result of the earth's rotation. When air currents develop, they are deflected to the right or left, depending on which hemisphere you are in. This is why low pressure systems and hurricanes in the northern hemisphere have winds that rotate counterclockwise around their center. In the southern hemisphere, low pressure system's winds rotate clockwise around their center.

Gravity Waves - These waves occur between any stable layers of fluids of different density. When the fluid boundary is disturbed, buoyancy forces try to restore the equilibrium. The fluid returns to its original shape, overshoots and oscillations then set in, which propagate as waves. Gravity or buoyancy is the restoring force. A crude example of what gravity waves look like can be seen when you throw a rock in a calm pond. The ripples that spread out across the pond can be compared to propagating gravity waves.

Glory - An optical phenomena that consists of colorful rings that appear around the shadow of an object when the shadow is cast onto a cloud deck below the objects elevation. A glory consists of violet coloring on the inner portion, while a reddish tint is seen on the outer edge. An airplane that casts a shadow on a cloud deck below it can create a glory that can be seen by passengers in the plane.