Tropic of Cancer - The Tropic of Cancer is a line of latitude circling the Earth at approximately 23.5 degrees north of the equator. It is the northernmost point on Earth where the sun's rays can appear directly overhead. This occurs each year at noon on the day of the summer solstice.

Precipitable Water - This takes into account all the water vapor that is found in the atmosphere from the surface to a specified height. Precipitable water is the amount of liquid precipitation that would occur if all the water vapor were condensed. The measurement is given in inches of rain. Precipitable water values are watched closely by meteorologists when diagnosing the potential for heavy rains during weather events.

Contrail - A contrail is the condensation trail that is left behind by a passing jet plane or rocket. Contrails form when hot humid air from jet exhaust mixes with ambient air that is colder and drier. Contrails are composed of water droplets, and can therefore be thought of as a man-made cloud streak.

Tornado Warning - One is issued by the National Weather Service when a tornado is indicated by the WSR-88D radar or sighted by spotters; therefore, people in the affected area should seek safe shelter immediately. They can be issued without a Tornado Watch being already in effect. Tornadic thunderstorms commonly produce large hail and damaging winds as well.

Cloudburst - A sudden, heavy rain shower that tends to be localized and of a brief duration. Most cloudbursts occur within thunderstorms.

Advection Fog - Advection fog often looks like radiation fog and is also the result of condensation. However, the condensation in this case is caused not by a reduction in surface temperature, but rather by the horizontal movement of warm moist air over a cold surface. This is very common during the winter when warm moist winds blow over cold snowcover. Advection fog may also form when moist maritime air masses drift over a cold inland area. This usually happens at night when the temperature of the land drops due to radiational cooling.

Zodiacal Light - A softly luminous cone of white light visible from an hour or so after sunset or before dawn. The cause of this pre-dawn or post-dusk light is created by sunlight that reflects off of grains of dust in space between the Earth and the Sun. To an unknowing observer it can be mistaken for a glare of city lights on the distant horizon.