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.

Mist - A visible collection of tiny water droplets suspended in the atmosphere that can reduce visibility to as low as 5/8 of a mile. It does not reduce visibility as much as fog and is often confused with drizzle. Drizzle falls to the ground, while mist hangs in the lower atmosphere.

Tropopause - Zone of the atmosphere that marks the transition between the troposphere below and the stratosphere above. The tropopause is the top of the troposphere. 75 percent of the mass of the atmosphere is located below the tropopause. The height of the tropopause varies between 4 to 12 miles.

Hadley cell - A thermally driven air circulation in tropical and subtropical latitudes of both hemispheres. The Hadley cell resembles a huge convective cell with rising air near the equator and sinking air in the subtropical latitudes. This concept was first introduced by George Hadley in 1735.

Katabatic wind - A downslope wind that flows from high elevations down to the valleys or plains below. Katabatic winds are driven by the fact that cold air is heavier and more dense than relatively warmer air. When cold air pools in higher elevations and becomes significantly colder than the air below, the heavier air accelerates down into the lower elevations. Katabatic winds are most common near the elevated ice sheets of Antarctica and Greenland and can exceed hurricane force at times.

Loaded Gun (Sounding) - A description of the state of the atmosphere that is characterized by extreme instability. Loaded gun soundings contain a stable layer, called a cap, that must be broken through in order for the instability to be unleashed. If the cap is overcome, rapid development of strong to severe thunderstorms can be expected.

Transpiration - The process by which water escapes plants into the air and turns into water vapor. The rate at which plants lose water to the air increases as the temperature increases. Corn plants transpire at a rate higher than most plants. This means that corn needs more moisture to survive compared to most plant life.