Frontolosis - The dissipation of a frontal zone due to a weakening contrast between two air masses. The temperature gradient weakens during frontolysis, meaning the rate of change of the temperature along the frontal boundary is lessening. At the end of frontolysis, the front no longer exists. The opposite of frontolysis is frontogenesis.

Updraft - A stream of air that accelerates upward from the surface. The strongest updrafts are found within thunderstorms. Strong thunderstorms can see updraft speeds of over 100 mph!

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

Solstice - There are two solstices that occur each year. They are known as the summer and winter solstice. These are the times of year the sun is either at its highest or lowest angle in the sky. The largest amount of sunlight in a day is seen during the summer solstice while the shortest amount of sunlight in a day is seen on the winter solstice.

Jet Stream - Intense winds that are concentrated in a relatively narrow stream in the upper atmosphere. Most jet streams are found at around 30,000 ft up in the atmosphere. The two jet streams that impact the US are the polar and subtropical. Both act as highways for weather systems to travel along.

Astronomical Twilight - Is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 18 degrees below the horizon. Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening, scattered light from the Sun is less than that from starlight and other natural sources. Before and after astronomical twilight, the sky is absolutely dark.

Trough - A sharpened zone of cyclonic wind change usually associated with a zone of lower pressure. Troughs can occur at the surface up to around 30,000 ft up in the atmosphere. Deep troughs in the mid to upper levels tend to be associated with surface frontal boundaries and surface low pressure systems. Inclement weather can be expected when a trough moves through a particular area.