6.1 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Glossary of meteorology | 6/25 | https://en.wikipedia.org/wiki/Glossary_of_meteorology | reference | science, encyclopedia | 2026-05-05T07:51:09.813841+00:00 | kb-cron |
corona An optical phenomenon consisting of apparent concentric, pastel-colored rings around a bright celestial object (such as the Sun or the Moon), which are produced by the diffraction of light by individual water droplets or sometimes small ice crystals in a cloud or on a foggy glass surface. Coronae differ from halos in that the latter are formed by refraction from comparatively large particles.
crepuscular rays
crosswind Any wind that moves in a direction that is perpendicular to the direction of travel of a reference object, such as an airplane.
Crow instability Also vortex Crow instability. An inviscid line-vortex instability most commonly observed in the skies behind large aircraft such as the Boeing 747. It occurs when the wingtip vortices interact with contrails from the engines, producing characteristic visual distortions in the shapes of the contrails.
cumuliform Of or relating to heaped, "puffy" clouds, such as cumulus or cumulonimbus, that form as a result of atmospheric convection.
cumulonimbus
cumulus (Cu) A genus of cloud characterized by low-level "puffy" or "cotton-like" forms with flat bases (generally opaque white in color but sometimes with grey undersides), which occur individually or multiply in a variety of distinct subforms, usually at altitudes less than 2 km (6,600 ft) above sea level. Cumulus clouds normally produce little or no precipitation, but can develop into precipitation-bearing clouds such as cumulonimbus when influenced by atmospheric instability, moisture, and temperature gradients.
cumulus congestus
cumulus humilis
cumulus mediocris
cyclone Any large-scale air mass characterized by inward spiraling winds which circulate around a strong center of low atmospheric pressure. Cyclones can form over land or water, can vary in size from mesocyclones such as tornadoes to synoptic-scale phenomena such as tropical cyclones and polar vortices, and may transition between tropical, subtropical, and extratropical phases. Contrast anticyclone.
cyclonic rotation
cyclogenesis The development or strengthening of a cyclonic circulation in the atmosphere. Cyclogenesis may refer to a number of different processes that occur under a variety of conditions and at a variety of scales, all of which result in the formation of some sort of cyclone; for instance, tornadoes are a type of mesocyclone whose development may be variously described as cyclogenesis or, more specifically, tornadogenesis. Contrast anticyclogenesis.
== D ==
dark adaptor goggles Also red adaptation goggles. A type of specialized eyewear used by meteorologists and astronomers for adapting the eyes to the dark prior to an observation made at night, or for aiding with identification of clouds during bright sunshine or when there is a glare from snow.
dawn Also daybreak. The first appearance of sunlight in the eastern sky before sunrise, or the time that marks the beginning of the morning twilight.
daytime The period of the day between sunrise and sunset, during which any given point on the Earth experiences natural illumination from especially direct sunlight, known as daylight.
dBZ Abbreviation of decibel relative to Z
debris cloud See tornado debris signature.
deepening A decrease in the central and surrounding sea-level pressure within the circulation of a pressure system (usually a low-pressure system) over a short period of time, with the result that mass is exported from the total air column overlying the system faster than it is supplied. Deepening of a low is commonly accompanied by the intensification of its cyclonic circulation and hence its winds, and the term is frequently used to imply cyclogenesis. Contrast filling.
deflation The removal of snow, dust, sand, or other loose material from a surface by the action of the wind.
deformation The rate of change of shape of a fluid body such as an air mass. This quantity is very important in the formation of atmospheric fronts, in the explanation of cloud shapes, and in the diffusion of materials and properties through the atmosphere.
degree-day A measure of the difference between the mean daily temperature and a specified reference temperature for a given day. For a specified period, e.g. a month or a year, the number of degree-days is the sum of all degree-days within that period.
dense fog An advisory issued by the U.S. National Weather Service to caution the public about the possibility that horizontal visibility may be reduced by dense fog to 0.25 miles (0.40 km) or less.
depression Any area of low atmospheric pressure at a given level in the atmosphere; i.e. a "low" or trough. The term is used especially frequently to refer to an early stage in the development of a tropical cyclone during which the disturbance is only weakly developed or poorly organized; see tropical depression.
derecho A type of storm that produces widespread, straight-lined sustained winds that are associated with severe thunderstorms.
dew Liquid water droplets that commonly appear on thin, exposed surfaces in the morning or evening due to the condensation of atmospheric moisture on radiatively cooled surfaces. When temperatures are low enough, the water droplets freeze into ice particles known as frost.
dew point (Td) Also dewpoint or dew-point. The temperature to which an air parcel must be cooled, at constant pressure and moisture content, in order for saturation to occur. Continued cooling below the dew point will cause condensation of water droplets if atmospheric conditions are favorable. Dew point is often used as a proxy by which to indicate the moisture content of the air.
dew point depression (T–Td) The difference between the actual temperature and the dew point at a certain altitude in the atmosphere. A small dew point depression indicates more moisture and higher relative humidity, which in the lower troposphere can result in low cloud bases and lifted condensation levels, which are important factors contributing to the development of severe thunderstorms.