Weather glossary

A complete weather glossary with 27 weather terms. Easy-to-understand explanations of weather phenomena, units of measurement and technical terms.

27 Terms 14 Categories 13 Letters
Category: Climate (2) Cloud cover (1) Forecast (1) Fronts (1) Humidity (2) Optical phenomena (2) Weather phenomena (1) Air pollution (2) Precipitation (3) Atmospheric pressure (3) Radiation (1) Storms (2) Temperature (3) Wind (3)

A

Atmospheric pressure (Atmospheric pressure) The weight of the air above a point. High pressure usually means settled weather; low pressure bring… Anticyclone (Anticyclone) A high-pressure area. It brings clear skies and dry, stable weather, though in winter it can trap pe… Air quality index (AQI) (Air quality index (AQI)) A scale summarising how polluted the air is from particles and gases (PM2.5, PM10, ozone, NO2). The …

C

Cloud cover (Cloud cover) The fraction of sky covered by cloud. It affects temperature: at night clouds trap heat, and by day … Cold front (Cold front) The boundary where a cold air mass pushes out a warmer one. It usually brings showers or storms and,…

D

Dew point (Dew point) The temperature at which the air becomes saturated and water vapour starts to condense. The higher i… Dust haze (calima) (Dust haze) Dust or sand suspended in the air, often from the Sahara, which clouds the sky, cuts visibility and …

E

El Niño (El Niño) A periodic warming of the equatorial Pacific that disrupts global weather. In South America it tends…

F

Feels-like temperature (Feels-like temperature) The temperature the body actually perceives, not what the thermometer reads. Wind makes it feel cold… Fog (Fog) A cloud at ground level that cuts visibility below 1 km. It forms when air cools to its dew point. Frost (Frost) A drop in ground-level temperature to 0 °C or below, freezing dew and damaging crops. It is most int…

H

Hail (Hail) Balls of ice formed in intense storms with strong updrafts. It can damage crops, vehicles and roofs. Hurricane (Hurricane) A tropical cyclone with sustained winds above 119 km/h. In the Atlantic and Caribbean the season run… Heat wave (Heat wave) A spell of several days with temperatures well above normal, including at night. It is a serious hea…

L

Low-pressure system (Low-pressure system) A low-pressure area of unstable air. It generates clouds, rain, wind and changeable weather. In the … La Niña (La Niña) The opposite phase to El Niño: a cooling of the equatorial Pacific. It tends to intensify rain in so…

P

Precipitation (Precipitation) Water falling from clouds as rain, drizzle, snow or hail. Measured in millimetres, equivalent to lit… Probability of precipitation (Probability of precipitation) How likely it is to rain at a given place and time. 60 % does not mean heavy rain, but a 60 % chance…

R

Relative humidity (Relative humidity) The amount of water vapour in the air as a percentage of the maximum it could hold at that temperatu…

T

Temperature (Temperature) A measure of how warm the air is. It is read in the shade, 2 metres above the ground. It is the most… Thunderstorm (Thunderstorm) A storm with lightning and thunder, heavy rain, wind gusts and sometimes hail. The safest thing duri…

U

UV index (UV index) A 0 to 11+ scale measuring the strength of the sun's ultraviolet radiation. From 6 (high) you should…

V

Visibility (Visibility) The greatest distance at which objects can be made out. It drops with fog, heavy rain, dust or smoke…

W

Wind speed (Wind speed) How fast the air is moving. Expressed in km/h, m/s or knots, and often on the Beaufort scale. Wind gust (Wind gust) A brief, sudden increase in wind speed. Gusts, not the average wind, are what bring down trees and c… Wind direction (Wind direction) The compass point the wind comes from. A north wind blows from the north towards the south. It deter… Weather radar (Weather radar) An instrument that detects rain, snow and hail in real time and shows where they are moving. It is t…