- 行业: 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, ...
In air navigation, the angle between an aircraft's course and its heading required to maintain that course against the wind. See single drift correction, multiple drift correction.
Industry:Weather
Any sea ice that has drifted from its place of origin. The term is used in a wide sense to include any areas of sea ice, other than fast ice, no matter what form it takes or how disposed.
Industry:Weather
The current computed by dividing the distance moved by a real object, or hypothetical particle moving with the fluid, by the time during which the movement takes place.
Industry:Weather
A card, such as is used in a drift bottle, encased in a buoyant, waterproof envelope and released in the same manner as a drift bottle, for the purpose of estimating the surface current in a body of water. Cheaper and lighter than bottles, drift cards are especially suited to dropping in large quantities from aircraft, and it is assumed that the card, having less freeboard than a bottle, is less affected by wind.
Industry:Weather
A bottle, of one of various designs, that is released into the sea for use in studying currents. It contains a card, identifying the date and place of release, to be returned by the finder with the date and place of recovery. The bottle should be so designed and ballasted as to minimize direct wind effects. Since the path of a bottle can only be estimated between release point and recovery, and generally only a few percent are returned, this is an inefficient, although inexpensive, technique. Compare drift card.
Industry:Weather
A nocturnal, thermally forced along-valley wind produced as a result of nocturnal cooling of the valley air; a nocturnal component of the fair- weather mountain–valley wind systems encountered during periods of light synoptic or other larger-scale flow. Valley cooling is accomplished by the combined effects of draining cold air off the slopes by early-evening downslope (katabatic) winds, and upward motion with upward cold-air advection from the convergence of katabatic flows in the valley center. Air in the valley thus becomes cooler than air at the same level over the adjacent plain (see topographic amplification factor), producing higher pressure in the valley. The pressure gradient drives a downvalley wind that begins one to four hours after sunset, persists for the rest of the night until after sunrise, and often reaches 7–10 m s−1 or more above the surface. The downvalley wind tends to fill the valley, that is, its depth is approximately the depth of the valley, and where mountains end and a valley empties onto the plains, the downvalley wind can become a cold-air valley outflow jet flowing out of the mouth of the valley. See drainage wind, along-valley wind systems.
Industry:Weather
1. The effect of the velocity of fluid flow upon the velocity (relative to a fixed external point) of an object moving within the fluid; the vector difference between the velocity of the object relative to the fluid and its velocity relative to the fixed reference. In air navigation, drift is often couched in terms of angular difference between heading and course, and thus can be produced only by a crosswind; when the wind velocity is parallel to the heading of the aircraft (direct headwind or tailwind), the drift is considered to be zero. The calculation of the drift (leeway) effects upon an ocean-going vessel is complicated by having to consider the combined effects of two fluids in motion. 2. “In geology, materials in transport by ice; deposits made by glacial ice on land, in the sea, and in bodies of meltwater. ” (Glossary of Arctic and Subarctic Terms, 1955. ) 3. The speed of an ocean current. In publications for the mariner, drifts are usually given in miles per day or in knots. 4. See snowdrift. 5. The horizontal track of an object, for example, clouds, caused by the wind or fluid motion. Also refers to a shift in the calibration of a satellite sensor or change in the orbital track of a satellite.
Industry:Weather
Sea ice from the surface of which meltwater has disappeared after the formation of cracks and thaw holes. During the period of drying, the surface whitens.
Industry:Weather
A ventifact with three edges and three facets formed by wind abrasion. Conditions of formation seem to require regions having scanty vegetation, strong winds, and sand and pebbles as a common surface cover. They occur in many parts of the Arctic, particularly in periglacial regions. As such they are used as tentative indicators of past conditions, both climatic and geological.
Industry:Weather
