60 articles
ACTIVATE (field campaign)
ACTIVATE (Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment) was a NASA airborne field campaign studying aerosols, clouds, and meteorology over the western North Atlantic.
Aerosol indirect effect
The aerosol indirect effect is the change in Earth's radiation balance caused when airborne particles modify clouds, a cooling that is the most uncertain climate forcing.
Aerosol-cloud interaction
Aerosol-cloud interaction is the process by which atmospheric aerosol particles alter cloud microphysics, radiation, and precipitation, assessed by the IPCC as the largest single uncertainty in near-term climate projections.
Aggregation (cloud physics)
Aggregation in cloud physics is the process by which ice crystals collide and stick together inside clouds, forming large irregular snowflakes; it is a key process in precipitation growth.
Altocumulus cloud
Altocumulus is a mid-level cloud genus of white or gray patches of rounded cloudlets, one of ten WMO cloud genera, usually signaling settled weather but with castellanus forms preceding thunderstorms.
Altostratus cloud
Altostratus is one of the ten basic cloud genera, a mid-level gray or bluish sheet through which the sun appears dimly, sometimes producing virga or very light precipitation.
Anvil cloud
An anvil cloud, formally called incus, is the flat, spreading icy top of a mature cumulonimbus storm cloud, formed where rising air meets a stable layer.
Arcus cloud
The arcus cloud, also called an arc cloud, is a dense, low, horizontal roll or wedge cloud forming along a thunderstorm's gust front, as shelf or roll clouds.
Bergeron process
The Bergeron process, also called the Wegener–Bergeron–Findeisen process, is the mechanism by which ice crystals in cold clouds grow at the expense of supercooled water droplets.
Brocken spectre
A Brocken spectre is the observer's own shadow, apparently enormously magnified, cast onto fog or cloud when the observer stands above the cloud layer with a low sun behind them.
Circumhorizontal arc
The circumhorizontal arc, often called a fire rainbow, is a colorful band of light formed when sunlight refracts through flat, plate-shaped ice crystals in cirrus clouds, visible only where the sun climbs above 58°.
Cirrocumulus cloud
Cirrocumulus (Cc) is one of the ten cloud genera: a thin, white, high-level cloud of small grains or ripples, mostly ice crystals and usually short-lived.
Cirrostratus cloud
Cirrostratus is one of the ten WMO cloud genera, a transparent whitish veil of ice crystals at 20,000 to 40,000 ft that generally produces halos and often signals an approaching warm front.
Cirrus cloud
Cirrus is a genus of thin, high-altitude clouds made of ice crystals, appearing as delicate white filaments or bands and covering more than half the planet.
Cloud
A cloud is a visible mass of minute water droplets or ice crystals that forms when water vapor condenses in the atmosphere, ranging from thin high-altitude veils to thunderstorm towers.
Cloud albedo
Cloud albedo is the fraction of incoming solar radiation that a cloud reflects back to space; higher albedo leaves less energy to heat the surface, cooling the climate.
Cloud base
The cloud base is the lowest level at which the air within a cloud contains a perceptible quantity of cloud particles, a standard observation critical to aviation safety.
Cloud condensation nuclei
Cloud condensation nuclei (CCN) are tiny airborne aerosol particles, up to about one micrometer in size, on which water vapor condenses to form cloud droplets and influence climate.
Cloud iridescence
Cloud iridescence, sometimes called a rainbow cloud, is an optical phenomenon in which thin clouds show patches of color, produced when small droplets or ice crystals diffract sunlight.
Cloud physics
Cloud physics, or cloud microphysics, is the branch of atmospheric science that studies how clouds form and evolve, covering droplet nucleation, ice formation, precipitation, and their climate effects.
Cloud seeding
Cloud seeding is a weather modification technique that introduces particles such as silver iodide or dry ice into existing clouds to increase rain or snowfall.
Collision-coalescence process
The collision-coalescence process, or warm rain process, forms rain in clouds warmer than freezing: droplets of different sizes fall at different speeds, collide, and merge into raindrops.
Condensation
Condensation is the phase change in which water vapor becomes liquid water, the reverse of vaporization. It turns cooling, rising air into cloud and releases latent heat.
Contact nucleation
Contact nucleation, also called contact freezing, is a mode of ice nucleation in which a supercooled cloud droplet freezes when an ice-nucleating particle touches its surface.
Contrail
A contrail, also called a condensation trail or vapor trail, is a line-shaped ice-crystal cloud that forms behind high-flying aircraft, from engine exhaust condensing or from pressure changes around wings.
Cumulonimbus cloud
The cumulonimbus cloud (Cb) is a vertically developed convective cloud known as a thunderhead, one of the ten basic cloud genera, and the cloud that produces thunderstorms, lightning, and hail.
Cumulus cloud
Cumulus, from the Latin for heap, is a low-level cloud genus of dense, heaped, cauliflower-shaped clouds formed by convection; it usually signals fair weather but can grow into thunderstorm-producing cumulonimbus.
Effective radius (cloud physics)
The effective radius in cloud physics is a characteristic droplet radius, defined as the ratio of the third to the second moment of the particle size distribution.
Equilibrium level
The equilibrium level, also called the level of neutral buoyancy or limit of convection, is the height where a rising air parcel again equals its environment's temperature, approximating the height of thunderstorm tops.
EUREC4A
EUREC4A, an international field campaign over the tropical Atlantic east of Barbados in 2020, used four aircraft and research vessels to study trade cumulus clouds and climate sensitivity.