- 行业: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
1. The study of ice and snow. 2. In Europe, a synonym for glaciology. Note: The term cryology has become almost meaningless unless it is defined in context. (Arctic and Subarctic Terms, Arctic, Desert Tropic Information Center Pub. A-105, 1955. ) 3. The study of sea ice.
Industry:Weather
A basic inference rule used in most expert systems. If A implies B and B implies C, then it is also true that A implies C. For example, if the fact that it is July in Boston implies that the temperature is above freezing, and having the temperature above freezing implies that no precipitation will reach the ground as snow, it follows that it will not snow in Boston in July.
Industry:Weather
1. The statement that in the horizontal flow of an inviscid barotropic fluid, the vertical component of absolute vorticity of each individual fluid particle remains constant. The principle was first applied to the atmosphere by Rossby and is the dynamical principle underlying the nondivergent barotropic model of the atmosphere. See constant absolute vorticity trajectory. 2. The hypothesis that the vorticity of individual eddies is conserved during the turbulent mixing of a fluid. See vorticity-transport hypothesis.
Industry:Weather
1. The state of a layer of unsaturated air when its lapse rate of temperature is less than the dry-adiabatic lapse rate but greater than the moist-adiabatic lapse rate. Under such conditions a parcel of air at the environmental temperature is unstable to upward vertical displacements if it is saturated, unstable to downward displacements if it is saturated and contains cloud water, but stable to all small vertical displacements if it is unsaturated. For descending air containing only rain water, the stability depends on both the lapse rate and the drop-size distribution. This definition does not require that such a parcel be obtained by adiabatic displacement from any level. It also does not require that the energy released from latent heating (CAPE) be greater than the convective inhibition (CIN) required to bring the parcel to its level of free convection. 2. Similar to definition 1 except that it must be possible for a parcel displaced adiabatically from some level and with conservation of total water mixing ratio to attain the environmental temperature in a saturated state. The choice of usage of the term “conditional instability” has been uncertain and sometimes controversial for at least 50 years. Haurwitz defined it approximately as definition 1, and this has been most frequently accepted. However, Byers used a definition similar to definition 2. Beers separated the definition into three subdefinitions, “stable type,” corresponding to definition 1 when a moist parcel cannot be obtained, and “pseudolatent”and “real latent,” corresponding to definition 2 but with the last requiring essentially that CAPE be greater than CIN. Dutton subscribes to the Haurwitz definition, while Emanuel develops a definition similar to definition 2, but with elaboration similar to that of Beers.
Industry:Weather
1. The rounded portion of a comma cloud system. This occurs to the left of the maximum wind speed axis and contains the most rotation when viewed in motion. This region often produces most of the steady precipitation. 2. A cloud pattern seen on satellite imagery, shaped like the upper part of a comma, without the tail. It is often associated with cyclonic development.
Industry:Weather
1. The movement of water under or around a structure built on permeable foundations that may lead to erosion. 2. The slow, downslope movement of surface soil or rock debris, usually imperceptible except when observed for long durations.
Industry:Weather
1. The portion of a comma cloud system that lies to the right of, and often nearly parallel to, the axis of maximum winds. 2. A cloud pattern seen on satellite imagery, shaped like the lower part of a comma, without the head. The tail is often associated with a cold front.
Industry:Weather
1. The portion of the streamflow during any month or year derived from precipitation in previous months or years. 2. Storage of water during a wet surplus year used for making up deficiencies in dry years.
Industry:Weather
1. The process by which various types of clouds are formed. In most cases, cloud formation involves cooling by expansion of ascending moist air. In rare exceptions, the cooling may occur as a result of other processes such as mixing, as in a contrail. The ascent of air may result from vertical instability, as in most cumulus clouds; from undulatory motions at inversion surfaces, as in certain undulatus species; from orographic lifting; and at a frontal surface, as in many altostratus and other stratiform clouds. 2. A particular arrangement of clouds in the sky, or a striking development of a particular cloud.
Industry:Weather
1. The property of a single wave with a phase that is a continuous, linear function of position at a given time. A stable local oscillator produces a coherent wave. 2. The property of two or more waves that are in phase both temporally and spatially. Waves are coherent if they have the same wavelength and a fixed phase relationship with each other. When the phase relationships are not fixed, the waves are said to be partially coherent or incoherent. 3. The correlation coefficient between electromagnetic fields at points separated in space and time, sometimes called degree of coherence. So defined, the coherence equals unity for waves that are perfectly coherent and is less than unity for partially coherent waves. 4. As used by Sir Gilbert Walker (1932), the statistical persistence exhibited by successive daily values of atmospheric pressure at any one location.
Industry:Weather
