The level in the atmosphere at which a parcel of air reaches saturation.

Warm, humid air masses that form in tropical regions.

The twice-yearly occurrence (about March 21 and September 21) when the sun at its highest point crosses the equator.

The mass of air surrounding the Earth.

The average of a series of temperatures taken over a period of time, such as a day or a month.

A sudden shift in wind direction.

The direction from which the wind is blowing.

The conditions in the atmosphere at any given time.

A small cyclonic circulation in the early stages of development that moves along a cold front.

A stationary cloud formed by the air "bouncing" over a mountain range.