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Section D D index 161-169 of 573 terms Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Next depression—1. In general, a point or limited area of locally lower elevation in a particular surface. 2. In meteorology, an area of low pressure; a low or trough. This is usually applied to a certain stage in the development of a tropical cyclone, to migratory lows and troughs, and to upper-level lows and troughs that are only weakly developed. This use of the term is most common in the European literature. See V-shaped depression. 3. Same as depression angle. 4. See wet-bulb depression, dewpoint spread. depth–area curve—A curve showing the relation between an averaged areal rainfall depth and the area over which it occurs, for a specified time interval, during a specific rainfall event. depth–area–duration analysis—Compilation of depth–area curves for different time intervals on a single graph. depth–area–duration curves—Depth–area curves for different time intervals. depth–duration–area value—(Commonly abbreviated DDA value.) The average depth of precipitation that has occurred within a specified time interval over an area of given size. Usually, for any given storm or period of study, the assigned DDA values are those that represent the highest average depth for each selected duration and areal size. depth–duration curve—A curve giving the relation between averaged areal rainfall depth and time interval for specific events. depth–duration–frequency curve—Curves showing the time interval frequency for storms of specific areal rainfall. depth-first search—A search algorithm that extends the current path as far as possible before backtracking to the last choice point and trying the next alternative path. Depth-first search generally reaches a satisfactory solution more rapidly than breadth first, an advantage when the search space is large. However, unlike breadth first, it does not guarantee that the optimal solution has been found. Compare breadth-first search. depth hoar—1. Ice crystals (usually cup-shaped, faceted crystals) of low strength formed by sublimation within dry snow beneath the snow surface; a type of hoarfrost. Associated with very fast crystal growth under large temperature gradients. This is one way in which firn formation may begin. Depth hoar is similar in physical origin to crevasse hoar. 2. Hoarfrost composed of crystals that have built up a three-dimensional complex of faceted, rather than rounded, crystals. depth-integration sediment sampling—A methodology that obtains a representative discharge- weighted water–sediment sample over stream verticals, except in an unmeasured zone near the streambed, by continuously cumulatively collecting a portion of the water–sediment mixture as the sampler traverses the vertical at an approximately constant transit rate. Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Next