- Industry: Weather
- Number of terms: 60695
- Number of blossaries: 0
- Company Profile:
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, ...
A dry foehn wind from the northwest descending the coastal hills of Majorca.
Industry:Weather
A drop of water of diameter greater than 0. 5 mm falling through the atmosphere. In careful usage, falling drops with diameters between 0. 2 and 0. 5 mm are called drizzle drops rather than raindrops, but this distinction is frequently overlooked and all drops with diameters in excess of 0. 2 mm are called raindrops. The limiting diameter of 0. 2 mm is rather arbitrary, but has been employed because drops of this size fall rapidly enough (about 0. 7 m s<sup>−1</sup>) to survive evaporative dissipation for a distance of the order of several hundred meters, the exact survival distance being a function of the relative humidity. Drops much smaller than this limiting size fall so slowly from most clouds that they evaporate before reaching the ground. Virga is almost always composed of drops with diameters just below the limiting size assigned to drizzle drops. Raindrops are very much larger than cloud drops. A typical raindrop might have a diameter of 1–2 mm, while a typical cloud drop diameter is of the order of 0. 01–0. 02 mm. Raindrops fall between 2 and 12 meters per second (depending on altitude); those larger than about 1 mm are increasingly deformed by airflow (with flatter bases), the largest raindrops having a height to width ratio of 1:2. Raindrops may form by coalescence of cloud drops or from melting ice precipitation. Any given rainfall is characterized by a certain drop-size distribution of its raindrops, and even within a given storm this distribution may change its characteristics. The largest drops observed in heavy thunderstorms may have equivalent spherical diameters of 5–8 mm. Raindrops of such large size are rare, but occasionally form in the warm rain process by accretion of cloud water or can result from melting hail.
Industry:Weather
A dome used to cover the antenna assembly of a radar to protect it from the effects of weather. It may refer to either a surface-based or an airborne radar installation. Radomes must be made of material transparent to radio energy.
Industry:Weather
A diagram showing the trajectories of wave crests in shallow water under the influence of refraction.
Industry:Weather
A dispersion of raindrop water rebounding after reaching the earth's surface.
Industry:Weather
A disturbance in a snowfield caused by the simultaneous settling of a large area of thick snow crust or surface layer. It occurs when wind action has maintained the top foot or more as closely packed, fine-grained snow rather impervious to air movement. Meanwhile, at lower depths, firnification has caused the larger crystals (depth hoar) to grow at the expense of smaller ones, creating air pockets and a weak structure. The collapse of this structure (a perceptible drop, but rarely as much as 1 in. ) may be accompanied by a loud report; over a large, level field, adjacent patches may settle as a series of tremors. Occasionally, a snow geyser may be blown upward through the crack of a settling patch.
Industry:Weather
A division of the year according to some regularly recurrent phenomena, usually astronomical or climatic. See winter, spring, summer, autumn.
Industry:Weather
A device used to measure water levels. It consists of an adjustable, pointed metallic rod that is lowered until it just pierces the water surface. A hook gauge is a similar device, except that the rod is U-shaped, and the submerged hook is raised until the point just breaks the water surface.
Industry:Weather
