Science / Weather Glossary

Chromosphere: A thin layer of relatively transparent gases above the photosphere of the sun. It is observed best during a total eclipse of the sun.

Circulation: The flow or motion of a fluid in or through a given area or volume. In meteorology, it is used to describe the flow of air as it moves around a pressure system in the atmosphere. It describe . . . View Full Definition

Circulation Cells: Large areas of air movement created by the rotation of the earth and the transfer of heat from the equator toward the poles. Circulation is confined to a specific region, such as the tropics . . . View Full Definition

Cirriform: Clouds composed of small particles, mostly ice crystals. Because the particles are fairly widely dispersed, this usually results in relative transparency and whiteness, often producing a hal . . . View Full Definition

Cirrocumulus: A cirriform cloud with vertical development, appearing as a thin sheet of small white puffs which give it a rippled effect. It often creates a 'mackerel sky', since the ripples may look like . . . View Full Definition

Cirrostratus: A cirriform cloud that develops from cirrus spreading out into a thin layer, creating a flat sheetlike appearance. It can give the sky a slightly milky or veiled look. When viewed from the s . . . View Full Definition

Cirrus: One of the three basic cloud forms (the others are cumulus and stratus). It is also one of the three high cloud types. Cirrus are thin, wispy clouds composed of ice crystals and often appear . . . View Full Definition

Civil Twilight: The time between the moment of sunset, when the sun's apparent upper edge is just at the horizon, until the center of the sun is 6° directly below the horizon.

Clear: The state of the sky when no clouds or obscurations are observed or detected from the point of observation.

Clear Air Turbulence: Name given to turbulence that may occur in perfectly clear air without any visual in warning in the form of clouds. It is often found in the vicinity of the jet stream where large shears in . . . View Full Definition

Clear Ice: A glossy, clear, or translucent ice formed by the relatively slow freezing of large supercooled in water droplets. The droplets spread out over an object, such as an aircraft wing's leading . . . View Full Definition

Climate: The historical record and description of average daily and in seasonal weather events that help describe a region. Statistics are generally drawn over several decades. The word is derived fr . . . View Full Definition

Climate Analysis Center (CAC): The U.S. National Weather Service division that applies new technology and approaches to the analysis, diagnosis, and projection of short term climate fluctuations on a regional and global basis.

Climate Prediction Center (CPC): A branch of the National Centers for Environmental Prediction,the Center maintains a continuous watch on short-term climate fluctuations and diagnoses and predicts them.

Climatology: The study of climate. It includes climatic data, the analysis of the causes of the differences in climate, and the application of climatic data to the solution of specific design or operatio . . . View Full Definition

Clinometer: An instrument used to measure angles of inclination. Used in conjunction with a ceiling light, it determines cloud height at night, based on the angle of a projected light on the clouds, the . . . View Full Definition

Closed Low: A region of low pressure distinguished by a center of counterclockwise circulation (in the Northern Hemisphere), and is surrounded by one or more isobars or height contours. Closed lows alof . . . View Full Definition

Cloud: A visible collection of minute particle matter, such as water droplets and/or ice crystals, in the free air. A cloud forms in the atmosphere as a result of condensation of water vapor. Conde . . . View Full Definition

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