Meteopedia — Weather glossary
Weather encyclopedia with 342 terms
Browse detailed definitions of atmospheric phenomena, cloud types, measurement instruments, regional winds, meteorological scales, climatology and more.
A
Advection fog
Fog that forms when warm, moist air moves over a colder surface.
Atmospheric phenomenaAnticyclone
High-pressure system where descending air produces stable weather and clear skies.
Atmospheric phenomenaAurora borealis
Luminous phenomenon in the night sky caused by the interaction of solar particles with Earth's magnetosphere, visible at high latitudes.
Atmospheric phenomenaC
Clear-air turbulence
Atmospheric turbulence occurring in clear skies with no visual cues, the principal invisible hazard for aviation.
Atmospheric phenomenaCold front
Frontal boundary where cold air pushes under and lifts warm air, producing storms and a sharp temperature drop.
Atmospheric phenomenaD
DANA
Cut-off low: a cold air mass at upper levels detached from the jet stream, capable of triggering torrential rain.
Atmospheric phenomenaDepression
Low-pressure system associated with unstable weather, clouds, and precipitation.
Atmospheric phenomenaDowndraft
Column of rapidly descending air within or beneath a convective storm, capable of producing damaging winds when it hits the ground.
Atmospheric phenomenaDrop in cold air
Popular Spanish term for torrential rain events in the Mediterranean, associated with upper-level cold air over warm seas.
Atmospheric phenomenaDry haze
Suspension of mineral dust particles in the atmosphere reducing visibility without significant moisture, distinct from mist or fog.
Atmospheric phenomenaDry line
A boundary between a dry air mass and a moist air mass at the surface, frequently associated with severe thunderstorm formation.
Atmospheric phenomenaDust devil
Rotating column of rising air that picks up dust and debris from the ground, formed by intense local heating without connection to thunderstorms.
Atmospheric phenomenaE
Explosive cyclogenesis
Rapid deepening of an extratropical cyclone whose central pressure drops at least 24 hPa in 24 hours, generating hurricane-force winds. Also called a bomb cyclone.
Atmospheric phenomenaExtratropical cyclone
Low-pressure system forming outside the tropics from the contrast between cold and warm air masses, the main weather driver in mid-latitudes.
Atmospheric phenomenaF
Fire whirl
Fire vortex generated when a wildfire creates a convective column intense enough to produce rotation, with winds that can exceed 200 km/h.
Atmospheric phenomenaFog
Cloud at ground level that reduces visibility to less than 1,000 metres.
Atmospheric phenomenaFreezing fog
Fog consisting of supercooled water droplets that freeze on contact with cold surfaces, depositing a layer of crystalline ice (rime).
Atmospheric phenomenaG
H
Hadley cell
Tropical atmospheric circulation cell where air rises at the equator, moves poleward aloft, and descends at subtropical latitudes (~30°).
Atmospheric phenomenaHailstorm
An episode of hail precipitation, usually associated with severe thunderstorms with strong updrafts.
Atmospheric phenomenaHaze
Suspension of dust, sand or organic particles in the atmosphere that reduces visibility and gives the sky a yellowish tone.
Atmospheric phenomenaHoarfrost
Deposit of ice crystals forming on cold surfaces when water vapour sublimates directly to solid, typical of clear, calm nights.
Atmospheric phenomenaL
Lake-effect snow
Phenomenon whereby cold air masses crossing large warm lakes or seas generate intense bands of snow or showers on the downwind shore.
Atmospheric phenomenaLandspout
Weak tornado forming without a mesocyclone, through vertical stretching of surface vorticity beneath a developing convective cloud.
Atmospheric phenomenaLightning
Electrical discharge between a cloud and the ground, between clouds, or within a cloud, reaching temperatures of 30,000 °C.
Atmospheric phenomenaM
Mist
Suspension of microscopic water droplets in the atmosphere reducing visibility to between 1 and 5 km — thinner than fog but enough to blur the landscape.
Atmospheric phenomenaMonsoon
Seasonal wind system that reverses direction between summer and winter, creating wet and dry seasons.
Atmospheric phenomenaMountain wave
Oscillation of airflow passing over a mountain, generating turbulence, lenticular clouds, and vertical currents on the lee side of the terrain.
Atmospheric phenomenaMud rain
Precipitation carrying suspended Saharan dust that leaves a reddish or orange deposit on surfaces as it evaporates.
Atmospheric phenomenaR
Radiation fog
Fog formed by radiative cooling of the ground during clear, calm nights.
Atmospheric phenomenaRain shadow
Arid zone on the leeward side of a mountain range caused by moisture loss as air ascends and precipitates on the windward slope.
Atmospheric phenomenaRidge
Elongated extension of a high-pressure area on a synoptic chart, where isobars form an inverted "U", associated with stable weather and clear skies.
Atmospheric phenomenaRossby waves
Large-scale undulations of the jet stream and westerly winds caused by Earth's rotation, determining mid-latitude weather patterns.
Atmospheric phenomenaS
Sandstorm
Phenomenon in which strong winds lift large quantities of sand and dust from the ground, reducing visibility below 1 km.
Atmospheric phenomenaSea breeze front
Convergence line where the sea breeze collides with hot continental air, capable of triggering convective storms as it advances inland.
Atmospheric phenomenaSevere weather
Dangerous weather conditions including thunderstorms with large hail, destructive winds, tornadoes, torrential rain, or heavy snowfall.
Atmospheric phenomenaSnowstorm
Storm with heavy snowfall, strong winds, and very reduced visibility that can paralyse transport and produce significant snow accumulation in just a few hours.
Atmospheric phenomenaStationary front
Frontal boundary between two air masses that barely moves, causing persistent rain in the same area.
Atmospheric phenomenaT
Thermal low
Shallow low-pressure area generated by intense surface heating, without associated fronts, typical of summer over continental regions.
Atmospheric phenomenaThunderstorm
Weather phenomenon with lightning and thunder, produced by cumulonimbus clouds with strong convection.
Atmospheric phenomenaTorrential rain
Rainfall exceeding 60 mm/hour that can trigger flash floods, river surges, and landslides within a few hours.
Atmospheric phenomenaTropical storm
Tropical cyclone with sustained winds between 63 and 118 km/h, the intermediate stage between a tropical depression and a hurricane, with closed circulation and organised rain bands.
Atmospheric phenomenaTrough
Elongated extension of a low-pressure area on a synoptic chart, where isobars form a "V" shape, channelling instability and precipitation.
Atmospheric phenomena