60 articles
Fallstreak hole
A fallstreak hole, also called a hole punch cloud or skypunch, is a large circular gap in a thin cloud layer of supercooled droplets, usually triggered by aircraft.
Fog
Fog is a suspension of microscopic water droplets in air at the Earth's surface, essentially a cloud in contact with the ground that reduces visibility below 1 kilometer.
Homogeneous freezing
Homogeneous freezing is the spontaneous freezing of a supercooled liquid droplet without a solid particle, occurring below about −38 °C and driving ice formation in cirrus clouds.
Ice nucleating particles
Ice nucleating particles (INPs) are the rare subset of atmospheric aerosols that trigger ice formation in supercooled clouds, with major sources including mineral dust, biological particles, and sea spray.
International Satellite Cloud Climatology Project
The International Satellite Cloud Climatology Project (ISCCP) is the first project of the World Climate Research Programme, established in 1982 to map global cloud properties from weather satellites.
June Gloom
June Gloom, also known as May Grey, is a Southern California weather pattern of cool, overcast skies in May and June, caused by ocean stratus clouds moving over the coast.
Kelvin-Helmholtz cloud
A Kelvin-Helmholtz cloud, or fluctus in the WMO Cloud Atlas, is a short-lived formation of curling, wave-like clouds caused by wind shear, and a source of clear-air turbulence.
Köhler theory
Köhler theory, formulated by Swedish meteorologist Hilding Köhler in 1936, combines the Kelvin and Raoult effects to predict when an aerosol particle activates into a cloud droplet.
Lifted condensation level
The lifted condensation level (LCL) is the altitude at which a rising unsaturated air parcel cools to saturation and condensation begins, used to estimate convective cloud bases.
Light pillar
A light pillar is a vertical shaft of light above or below a light source, caused by flat plate-shaped ice crystals in cold air reflecting it; over the Sun it is called a sun pillar, over the Moon a moon pillar.
Liquid water path
Liquid water path is a measure of the weight of liquid cloud droplets in the atmosphere above a unit surface area, routinely retrieved from microwave radiometers.
List of cloud types
The list of cloud types is the World Meteorological Organization's classification of clouds into ten genera, from cirrus to cumulonimbus, published in the International Cloud Atlas.
Mammatus cloud
Mammatus cloud, also written mamma, is a supplementary cloud feature of rounded pouches hanging from a cloud base, often on thunderstorm anvils, and is not a tornado signal.
Marine stratocumulus clouds
Marine stratocumulus clouds are low, layered clouds over the oceans that cover more of Earth's surface than any other cloud type and strongly reflect sunlight, making them a leading source of uncertainty in climate prediction.
Microphysics scheme
A microphysics scheme is a parameterization in atmospheric and climate models that computes cloud and precipitation processes, such as condensation and particle growth, at subgrid scales.
Mist
Mist is a suspension of microscopic water droplets in the air near the ground that reduces visibility but not below 1 kilometer, when it becomes fog.
Mixed-phase cloud
A mixed-phase cloud is a cloud containing supercooled liquid droplets and ice crystals together, found from the tropics to the poles and important for precipitation and climate.
Nimbostratus cloud
Nimbostratus is a gray, often dark cloud layer, diffuse because of continuously falling rain or snow, that forms mainly from thickening altostratus along warm fronts of mid-latitude cyclones.
Noctilucent cloud
Noctilucent clouds, also called polar mesospheric clouds, are the highest clouds on Earth, thin ice clouds near the mesopause that shine at night in summer.
Okta
Okta, Inc. (Nasdaq: OKTA) is an American identity and access management company whose cloud platform authenticates users and governs their access to applications, serving organizations from small businesses to Fortune 500 companies.
Pea soup fog
Pea soup fog, or pea-souper, is a thick yellowish or blackish fog colored by coal soot and sulfur dioxide, typified by London's fogs and the Great Smog of December 1952; the name comes from split-pea soup.
Polar stratospheric cloud
The polar stratospheric cloud, also called a nacreous or mother-of-pearl cloud, forms in the winter stratosphere at 15 to 30 km and drives Antarctic ozone depletion.
Pyrocumulonimbus
A pyrocumulonimbus, or pyroCb, is a thunderstorm generated by wildfire heat, officially named flammagenitus, that injects smoke high into the atmosphere and spreads embers and lightning.
Rainmaking
Rainmaking, also called artificial rain or pluviculture, is the attempt to produce or increase rainfall, practiced historically as ritual and today as cloud seeding, which began in 1946.
Rime ice
Rime ice is a white, milky, opaque deposit of granular ice that forms when supercooled fog or cloud droplets freeze rapidly on striking a cold surface.
Riming
Riming is the cloud physics process by which supercooled liquid droplets freeze onto falling ice particles, one of three major ice crystal growth mechanisms in clouds.
Stratocumulus cloud
Stratocumulus cloud is a low, gray or whitish cloud layer of rounded masses or rolls, the most common cloud type on Earth, covering about one-fifth of the planet.
Stratus cloud
Stratus cloud is a generally gray, low cloud layer with a fairly uniform base that may give drizzle, snow, or snow grains, sometimes forming from lifting fog.
Wall cloud
A wall cloud, or pedestal cloud, is a localized, often rotating lowering from a thunderstorm's rain-free base; rotating ones usually develop before strong or violent tornadoes.
Weather modification
Weather modification, also called weather control, is the deliberate alteration of weather, chiefly by seeding clouds with substances like silver iodide to increase rain or suppress hail.