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.

342 Meteopedia 16 categories
All (342) Atmospheric phenomena (50) Instruments (30) Scales and measurements (10) Clouds (36) Wind (34) Precipitation (24) Temperature (15) Cyclones and severe storms (14) Atmospheric optics (16) Meteorological astronomy (5) Climatology (34) Marine meteorology (15) Air quality (10) Agrometeorology (10) Hazards and safety (10) General (29)
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Altocumulus

Mid-level cloud in the form of white and grey patches, rolls or flakes, often in regular rows.

Clouds

Altostratus

Mid-level grey cloud that covers the sky like a veil, letting the sun show through diffusely.

Clouds

Arcus cloud

Accessory cloud in the form of a horizontal arch or roll appearing at the leading edge of intense storms.

Clouds

Asperitas

Cloud type officially recognised by the WMO in 2017, with a chaotic, wave-like underside resembling a rough sea viewed from below.

Clouds

B

Banner cloud

Cloud forming attached to an isolated mountain summit and extending leeward like a flag, caused by pressure drop and condensation in the lee vortex.

Clouds

C

Castellanus cloud

Cloud variety with vertical turrets or crenellations rising from a common base, indicating instability in the mid-levels of the atmosphere.

Clouds

Cavum

Circular or elliptical hole in a mid or high cloud layer caused by local glaciation of supercooled droplets, also known as a fallstreak hole or hole-punch cloud.

Clouds

Cirrocumulus

High cloud formed by small regular white tufts, giving a "mackerel sky" appearance.

Clouds

Cirrostratus

High, thin cloud forming a whitish, semi-transparent veil of ice crystals that partially or fully covers the sky and often produces solar or lunar halos.

Clouds

Cirrus

High cloud (6,000–12,000 m), thin and fibrous, composed entirely of ice crystals.

Clouds

Cloud ceiling

Height of the base of the lowest cloud layer covering more than half the sky, critical aviation data determining visual or instrument flight conditions.

Clouds

Contrail

An artificial line-shaped cloud created by aircraft exhaust gases at high altitude.

Clouds

Cumuliform cloud

A type of vertically developing cloud with a puffy appearance and flat base, formed by convective updrafts.

Clouds

Cumulonimbus

Towering cloud of enormous vertical development, associated with thunderstorms, lightning, hail, and heavy rain.

Clouds

Cumulonimbus incus

Mature stage of the cumulonimbus with the characteristic anvil top, indicative of severe storms with hail, lightning, and strong winds.

Clouds

Cumulus

Vertically developing cloud with a flat base and cauliflower-shaped top, typical of fair weather or storm development.

Clouds

Cumulus congestus

Towering cumuliform cloud with cauliflower-shaped turrets that can produce showers but has not yet developed an anvil or electrical activity.

Clouds

Cumulus humilis

Small cumuliform cloud of limited vertical extent, wider than tall, indicating fair weather and atmospheric stability.

Clouds

F

Fractus cloud

Irregular, ragged cloud fragments forming beneath rain clouds or in strong winds, with constantly changing edges.

Clouds

I

Iridescent cloud

Cloud displaying bright rainbow-like colours at its edges, produced by diffraction of sunlight passing through uniformly sized water droplets or ice crystals.

Clouds

K

Kelvin-Helmholtz wave cloud

Cloud formation with rolling wave crests resembling breaking ocean waves, caused by Kelvin-Helmholtz instability between air layers of different velocities.

Clouds

L

Lenticular cloud

Stationary lens-shaped cloud that forms downwind of mountains due to orographic waves.

Clouds

M

Mammatus

Rounded protuberances hanging from a cloud base, associated with severe storms.

Clouds

N

Nimbostratus

Dark grey cloud of great horizontal extent that produces continuous rain or snow.

Clouds

Noctilucent cloud

Extremely high clouds (80-85 km) formed by ice crystals in the mesosphere, visible only during twilight.

Clouds

O

Orographic clouds

Clouds formed by the forced ascent of air over a mountain barrier, remaining stationary above peaks while wind flows through them.

Clouds

P

Pannus

Layer of low, irregular, dark cloud fragments forming beneath precipitating clouds such as cumulonimbus or nimbostratus, also called accessory clouds.

Clouds

Pileus

A smooth cap-shaped accessory cloud that forms briefly above the top of a growing cumulus or cumulonimbus.

Clouds

Pyrocumulonimbus

Cumulonimbus generated by intense heat from a wildfire or volcano, capable of producing lightning, hail, and fire tornadoes, and injecting smoke into the stratosphere.

Clouds

S

Stratocumulus

Low cloud formed by rounded masses or rolls grouped in layers, partially grey and partially white.

Clouds

Stratus

Low, grey, uniform layer cloud that often covers the entire sky, producing drizzle.

Clouds

U

Undulatus cloud

Cloud variety displaying regular parallel undulations resembling sea waves, caused by atmospheric gravity waves.

Clouds

V

Virga

Precipitation that falls from a cloud but evaporates before reaching the ground.

Clouds

Volcanic ash cloud

Cloud of pulverised rock particles and volcanic glass emitted by an eruption, extremely dangerous for aviation due to its ability to melt jet engines.

Clouds

Volutus

Long, solitary, tube-shaped horizontal cloud that rolls about its axis, completely detached from other clouds. Includes the Australian Morning Glory phenomenon.

Clouds

W

Wall cloud

A low, often rotating cloud formation descending from the base of a cumulonimbus, frequently associated with severe thunderstorms and tornadoes.

Clouds