Weather Glossary
Understand common meteorological terms
A
Cyclone
A rotating low-pressure system. Tropical cyclones are the most intense form.
Front
The boundary between cold and warm air masses. Cold fronts move faster and bring severe weather.
B
Barometric Pressure
The force exerted by the atmosphere on Earth's surface. Standard sea level pressure is 1013.25 hPa.
Beaufort Scale
A 13-level wind speed classification system from 0 (calm) to 12 (hurricane).
C
Cloud Cover
The fraction of the sky covered by clouds.
Convection
Heat transfer through vertical atmospheric movement. Often causes local thunderstorms.
D
Dew Point
The temperature air must cool to for saturation. Higher dew point means more humidity.
H
High Pressure (H)
Area with pressure higher than surroundings. Usually brings clear, stable weather.
Humidity
The amount of water vapor in the air. Relative humidity is the percentage of maximum capacity.
J
Jet Stream
Fast-moving air currents high in the atmosphere that influence weather system movement.
L
Low Pressure (L)
Area with pressure lower than surroundings. Usually brings clouds, wind, and precipitation.
P
Precipitation
Water falling from the atmosphere, including rain, snow, hail, and sleet.
PM2.5 / PM10
Particulate matter by diameter. PM2.5 can penetrate deeper into lungs.
R
Radar
Equipment using radio waves to detect precipitation location and intensity.
S
Satellite
Device in space observing Earth's atmosphere and surface. Provides cloud images and temperature data.
Wind Chill / Heat Index
How the body actually feels temperature, considering wind and humidity effects.
T
Tornado
A violently rotating column of air extending from thunderstorm to ground.
Temperature
Measure of hotness or coldness. Commonly measured in Celsius or Fahrenheit.
U
UV Index
International measure of UV radiation strength, scale 0-11+.
V
Visibility
Maximum distance to see objects. Reduced by fog, smog, rain, or snow.
W
Warning / Advisory
Notifications of hazardous weather issued by meteorological services.