Science / Weather Glossary

Conduction: The transfer of heat through a substance by molecular action or from one substance by being in contact with another.

Confluence: A rate at which wind flow comes together along an axis oriented normal to the flow in question. The opposite of diffluence.

Constant Pressure Chart: A chart of a constant pressure surface in which atmospheric pressure is uniform everywhere at any given moment. Elements may include analyses of height above sea level, wind, temperature, an . . . View Full Definition

Constant Pressure Surface: A surface along which the atmospheric pressure is equal everywhere.

Continent: A large land mass rising abruptly from the deep ocean floor, including marginal regions that are shallowly submerged. Continents constitute about one-third of the earth's surface.

Continental Air Mass: An air mass with continental characteristics. It is a secondary characteristic of an air mass classification, signified by the small 'c' before the primary characteristic, which is based on . . . View Full Definition

Continental Shelf: The zone around the continents extending from the low-water mark seaward, typically ending in steep slope to the depths of the ocean floor.

Contrail: Acronym for CONdensation TRAIL. A cloud-like streamer or trail often seen behind aircraft flying in clear, cold, humid air. A vapor trail is created when the water vapor from the engine exha . . . View Full Definition

Convection: Motions in a fluid that transport and mix the properties of the fluid. These properties could be heat and/or moisture. When used to imply only upward vertical motion, it is then the opposite . . . View Full Definition

Convective Condensation Level (CCL): The height at which a parcel of air, if heated sufficiently from below, will rise adiabatically until it is just saturated.

Convergence: Wind movement that results in a horizontal net inflow of air into a particular region. Convergent winds at lower levels are associated with upward motion. Contrast with divergence.

Cooling Degree Day: A cooling degree day is given for each degree that the daily mean temperature departs above the baseline of 75 degrees Fahrenheit. It is used to estimate the energy requirements and is an in . . . View Full Definition

Coriolis Effect: A force per unit mass that arises solely from the earth's rotation, acting as a deflecting force. It is dependent on the latitude and the speed of the moving object. In the Northern Hemisphe . . . View Full Definition

Coromell: The prevailing evening land breeze which takes place from November to May in the vicinity of La Paz, at the southern tip of Baja California, Mexico.

Corona: A pastel halo around the moon or sun created by the diffraction of water droplets. The droplets in the cloud, such as cirrostratus, and the cloud layer itself must be almost perfectly unifor . . . View Full Definition

Corposant: A luminous, sporadic, and often audible, electric discharge. It occurs from objects, especially pointed ones, when the electrical field strength near their surfaces attains a value near 1000 . . . View Full Definition

Crepuscular Rays: Contrasting, alternating bright and dark rays in the sky. Sunlight is scattered by molecules and particles rendering these bright rays visible. Contrast is enhanced by haze, dust, or mist. T . . . View Full Definition

Crystallization: The process of a substance going directly from a vapor form (water vapor) to a solid (ice) at the same temperature, without going through the liquid phase (water). The opposite of sublimation.

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