An anabatic wind, it is formed during the day by the heating of the valley floor. As the ground becomes warmer than the surrounding atmosphere, the lower levels of air heat and rise, flowing up the mountainsides. It blows in the opposite direction of a mountain breeze.

An ocean or lake wave resulting from the action of wind on the water’s surface. After it leaves its fetch area, it is considered a swell.

Winds that blow in and around a cyclone, that is counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere.

Thunderstorms which develop after sunset. They are often associated with the strengthening of the low level jet and are most common over the Plains states. They also occur over warm water and may be associated with the seaward extent of the overnight land breeze.

A semi-continuous, semi-permanent boundary between polar air masses and tropical air masses. An integral part of an early meteorological theory known as the Polar Front Theory.

The measure of the strength of the westerly winds of the middle latitudes. It is expressed as the horizontal pressure difference between 35 degrees and 55 degrees latitude, or as the corresponding geostrophic wind.

The gaseous or air portion of the physical environment that encircles a planet. In the case of the earth, it is held more or less near the surface by the earth’s gravitational attraction. The divisions of the atmosphere include the troposphere, the stratosphere, the mesosphere, the ionosphere, and the exosphere.

The height at which a parcel of air, if heated sufficiently from below, will rise adiabatically until it is just saturated.

Considered a rotating cloud of debris or dust that is on the ground or near the ground. The debris cloud appearing beneath a thunderstorm will most likely confirm the presence of a tornado.

A warm dry wind on the lee side of a mountain range, whose temperature is increased as the wind descends down the slope. It is created when air flows downhill from a high elevation, raising the temperature by adiabatic compression. Classified as a katabatic wind.