Meteorology Glossary

The horizontal transport of an atmospheric property such as heat, moisture, or momentum by the wind.

An instrument that measures wind speed, often using rotating cups or an ultrasonic sensor.

A weather system characterized by high pressure at its center, with winds spiraling outward clockwise in the Northern Hemisphere. Generally associated with fair weather.

An instrument used to measure atmospheric pressure. Mercury and aneroid types are most common.

The vertical movement of air driven by buoyancy when the surface heats unevenly, often leading to cloud and storm development.

A weather system with low pressure at its center, with winds spiraling inward counterclockwise in the Northern Hemisphere. Associated with clouds and precipitation.

The temperature at which air reaches saturation and water vapor begins to condense into liquid water.

A strong downward current of air from a thunderstorm that produces damaging straight-line winds at or near the surface.

El Nino-Southern Oscillation; a coupled ocean-atmosphere climate phenomenon in the tropical Pacific that influences global weather patterns.

A theoretical wind resulting from a balance between the pressure gradient force and the Coriolis force, flowing parallel to isobars.

The leading edge of rain-cooled air (outflow) from a thunderstorm. Can trigger new convection along its boundary.

A measure of the amount of water vapor in the air. Can be expressed as relative humidity, specific humidity, or mixing ratio.

A line on a weather map connecting points of equal atmospheric pressure.

The rate at which atmospheric temperature decreases with increasing altitude. The environmental lapse rate averages about 6.5 degrees Celsius per kilometer.

The atmospheric scale of phenomena ranging from a few kilometers to several hundred kilometers, including thunderstorms, sea breezes, and squall lines.

A composite front formed when a cold front overtakes a warm front, lifting the warm air mass entirely off the surface.

Related to or caused by mountains. Orographic lift is the forced ascent of air over elevated terrain.

Any product of the condensation of atmospheric water vapor that falls from clouds, including rain, snow, sleet, and hail.

A balloon-borne instrument package that measures and transmits atmospheric temperature, humidity, and pressure as it ascends.

The ratio of the actual water vapor content of the air to the maximum it can hold at that temperature, expressed as a percentage.

A thermodynamic chart used by meteorologists to plot vertical profiles of temperature and dew point from radiosonde data to assess atmospheric stability.

A long-lived, rotating thunderstorm with a persistent mesocyclone. The most likely type of thunderstorm to produce tornadoes, large hail, and damaging winds.

The atmospheric scale of weather systems spanning hundreds to thousands of kilometers, including mid-latitude cyclones and anticyclones.

The boundary between the troposphere and the stratosphere, marked by a sharp decrease in the temperature lapse rate.

A measure of the rotation of air. Positive (cyclonic) vorticity in the Northern Hemisphere is associated with counterclockwise spin and storm development.