- Industry: Weather
- Number of terms: 60695
- Number of blossaries: 0
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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, ...
An observational day on which frost occurs; one of a family of climatic indicators (e.g., thunderstorm day, rain day). The definition is somewhat arbitrary, depending upon the accepted criteria for a frost observation. Thus, it may be 1) a day on which the minimum air temperature in the thermometer shelter falls below 0°C (32°F); 2) a day on which a deposit of white frost is observed on the ground; 3) in British usage, a day on which the minimum temperature at the level of the ground or on the tops of low, close-growing vegetation falls to −0. 9°C (30. 4°F) or below (also called a “day with ground frost”); and perhaps others. The present trend is to drop such terms in favor of something less ambiguous, such as “day with minimum temperature below 0°C (32°F). ”
Industry:Weather
An irregular surface in the ground that, at any given time, represents the penetration of thawing into seasonally frozen ground. In regions of permafrost, when the active layer is thawed completely, this coincides with the permafrost table. Compare frost line.
Industry:Weather
An irregular geometric object that is self-similar to its substructure at any level of refinement. The fractal dimension is a measure of the irregularity of the boundary of the object. Clouds have been shown to exhibit fractal characteristics with cloud perimeters having fractal dimension of about 1. 35. The result follows from the observation that over a large size range, cloud area is proportional to cloud perimeter raised to a power slightly less than 1. 5 (rather than proportional to the square of the perimeter, as is the case in Euclidean geometry); fractal dimension of the perimeter then is calculated as the ratio of 2 (the exponent in the Euclidean power law) to the exponent in the observed power relation.
Industry:Weather
An international code word used to indicate a flight forecast. A FIFOR is a trip forecast, that is, a forecast that progresses along with the aircraft.
Industry:Weather
An instrument, based on the principle of the geostrophic wind scale, for determining the geostrophic wind from data on a weather map.
Industry:Weather
An instrument, dropped from high altitude and carried by a stable parachute, used to measure the vertical component of turbulence aloft. It consists of an accelerometer and radio telemetering equipment.
Industry:Weather
An instrument used for the determination of the electrical conductivity of the atmosphere.
Industry:Weather
An instrument used for measuring geometric angles. See radio direction finder.
Industry:Weather
An instrument designed to measure the physiological cooling power in milligram- calories. It consists of a blackened copper sphere, diameter 7. 5 cm, the surface of which is maintained electrically at 36. 5°C against the heat losses due to all meteorological conditions of the ambient air.
Industry:Weather
