Science terms starting with D

722 terms

  1. Draft Hood A device built into or installed above a combustion appliance to assure the escape of combustion byproducts, to prevent backdrafting of the appliance, or…
  2. Draft sequence The sequence generated by the HGP as of June 2000 that, while incomplete, offers a virtual road map to an estimated 95% of all human genes.
  3. Drag Device on fishing reels that allows line to pay out under pressure, even though the reel is engaged; set correctly, it ensures against line breakage.
  4. Drain In medicine, to remove fluid as it collects; or, a tube or wick-like device used to remove fluid from a body cavity, wound, or infected area.
  5. Drain Layer A layer of permeable material in a dam to relieve pore pressure or to facilitate draining fill. See also, "Blanket"
  6. Drainage See Watershed.
  7. Drainage Area The area which drains to a particular point on a river or stream. The drainage area of a stream at a specified location is that area, measured in a…
  8. Drainage Basin All of the area drained by a river system. The drainage basin is a part of the surface of the earth that is occupied by a drainage system, which consists…
  9. Drainage Blanket A layer of pervious material placed directly over the foundation material to facilitate drainage of the foundation and/or embankment.
  10. Drainage curtain A line of vertical wells or boreholes to facilitate drainage of the foundation and abutments and to reduce water pressure (also called drainage wells or…
  11. Drainage Density The relative density of natural drainage channels in a given area. It is usually expressed in terms of miles of natural drainage or stream channel per…
  12. Drainage Divide The boundary line, along a topographic ridge or along a subsurface formation, separating two adjacent drainage basins.
  13. Drainage layer A layer of pervious material in an earthfill dam to relieve pore pressures or to facilitate drainage of the fill.
  14. Drainage system Collection of surface and/or subsurface drains, together with structures and pumps, used to remove surface or ground water.
  15. Drainage well (relief well) Vertical wells or boreholes downstream of, or in downstream shoulder of, an embankment dam to collect and control seepage through or under the dam and so…
  16. Drainback (Solar) Systems A closed-loop solar heating system in which the heat transfer fluid in the collector loop drains into a tank or reservoir whenever the booster pump stops…
  17. Draindown (Solar) Systems An open-loop solar heating system in which the heat transfer fluid from the collector loop and the piping drain into a drain whenever freezing conditions…
  18. Drainer A valley or basin from which air drains continuously during nighttime rather than becoming trapped or pooled.
  19. Drains (Relief Wells) A vertical well or borehole, usually downstream of impervious cores, grout curtains or cutoffs, designed to collect and direct seepage through or under a…
  20. Draw Same as to hit. Taking additional cards in an attempt to get closer to a total of 21.
  21. Drawdown Lowering a lake level for a specific purpose.
  22. DRCTN Direction
  23. Dredge To dig under water. A machine that digs under water.
  24. Dredging The scooping, or suction of underwater material from a harbor, or waterway. Dredging is one form of channel modification.
  25. DRFT Drift
  26. Drift See: genetic drift.
  27. Drift of ice Drift of ice Displacement of a sea ice field from its place of origin under the effect of ocean currents and winds.
  28. Drifting buoy Drifting buoy Floating (or drifting on ice) ocean buoy equipped with meteorological and/or oceanographic sensing instruments linked to transmitting…
  29. Drifting Ice Pieces of floating ice moving under the action of wind and/ or currents.
  30. Drifting Snow Drifting snow is an uneven distribution of snowfall/snow depth caused by strong surface winds. Drifting snow may occur during or after a snowfall.
  31. Drifting stations Drifting stations (drifting ice stations) Research stations on the floes of the Arctic Ocean.
  32. Drill An oblong tool made of flaked stone used in drilling holes in wood, leather or hides.
  33. Drip irrigation (trickle) An irrigation method in which water is delivered to or near each plant in small-diameter plastic tubing.
  34. Drizzle Precipitation consisting of numerous minute droplets of water less than 0.5 mm (500 micrometers) in diameter.
  35. Drop structure An in-stream structure of various materials designed to reduce the energy and force of stream flow.
  36. Drop-size Distribution The distribution of rain drops or cloud droplets of specified sizes.
  37. Drosophila melanogaster The fruit fly, used for many years as a model for eukaryotic genetics. Of the nearly 300 disease-causing genes in the human genome, more than half have an…
  38. Drought Climatic condition in which there is insufficient soil moisture available for normal vegetative growth. A prolonged period of below-average precipitation.
  39. Drought Assessments At the end of each month, CPC issues a long-term seasonal drought assessment. On Thursdays of each week, the CPC together with NOAA National Climatic Data…
  40. Drought Index Computed value which is related to some of the cumulative effects of a prolonged and abnormal moisture deficiency.
  41. drug Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition.
  42. drug delivery Method by which a drug is delivered to its site of action. For traditional drugs this is another name for formulation.
  43. Drum gate A movable crest gate in the form of a sector of a cylinder hinged at the centerline.
  44. Dry Adiabat A line of constant potential temperature on a thermodynamic chart.
  45. Dry Adiabatic Lapse Rate The rate at which the temperature of a parcel of dry air decreases as the parcel is lifted in the atmosphere.
  46. dry adiabatic lapse rate (DALR) The rate at which the temperature of a parcel of dry air decreases as the parcel is lifted in the atmosphere. The dry adiabatic lapse rate is 5.
  47. Dry Bulb Temperature The temperature of the air as measured by a standard thermometer.
  48. Dry closed-loop cooling See Dry cooling system
  49. Dry cooling See Dry cooling system
  50. Dry cooling system Also known as dry closed-loop cooling; a technology for rejecting heat from the steam condensate of a thermoelectric plant.
  51. Dry Crack Crack visible at the surface but not going right through the ice cover, and therefore it is dry.
  52. Dry Flood proofing A dry flood proofed building is sealed against floodwaters. All areas below the flood protection level are made watertight.
  53. Dry Floodproofing In hydrologic terms, a dry floodproofed building is sealed against floodwaters. All areas below the flood protection level are made watertight.
  54. Dry lake An ephemeral lake of an arid or semiarid region, typically found at low elevation points in desert valleys.
  55. Dry Line A boundary separating moist and dry air masses, and an important factor in severe weather frequency in the Great Plains.
  56. Dry Line Bulge A bulge in the dry line, representing the area where dry air is advancing most strongly at lower levels.
  57. Dry Line Storm Any thunderstorm that develops on or near a dry line.
  58. Dry Microburst A microburst with little or no precipitation reaching the ground; most common in semi-arid regions. They may or may not produce lightning.
  59. Dry Punch [Slang], a surge of drier air; normally a synoptic-scale or mesoscale process. A dry punch at the surface results in a dry line bulge.
  60. Dry Slot A zone of dry (and relatively cloud-free) air which wraps east- or northeastward into the southern and eastern parts of a synoptic scale or mesoscale low…
  61. Dry Steam Geothermal Plants Conventional turbine generators are used with the dry steam resources. The steam is used directly, eliminating the need for boilers and boiler fuel that…
  62. Dry Thunderstorm Generally a high-based thunderstorm when lightning is observed, but little if any precipitation reaches the ground.
  63. Dry Ton 2,000 pounds of material dried to a constant weight.
  64. Dry unit weight The weight of solid particles per unit of total volume. See unit weight.
  65. Dry wash A natural drainage channel that is typically dry, but conveys water following significant rainfall events and is subject to rapid flow during flash…
  66. Dry Weather Flow Streamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel.
  67. dry weight The weight of tissue obtained following sufficiently prolonged oven-drying at high temperature to remove all water.
  68. Dry well A deep hole, covered, and usually lined or filled with rocks, that holds drainage water until it soaks into the ground.
  69. Dry-adiabatic 1. An adiabatic process in a hypothetical atmosphere in which no moisture is present. 2.
  70. drying Moisture removal from biomass to improve serviceability and utility.
  71. DSA Special Tropical Disturbance Statement
  72. dscDNA See double\-stranded complementary DNA.
  73. dsDNA See: double-stranded DNA.
  74. DSIPT Dissipate
  75. Dst Index A geomagnetic index describing variations in the equatorial ringcurrent
  76. DTRT Deteriorate
  77. dTTP Rarely used but strictly correct abbreviation for deoxythymidine 5'-triphosphate. Required for DNA synthesis since it is a direct precursor molecule.
  78. dual culture A culture made of a plant tissue and one organism (such as a nematode) or an obligate parasite/micro-organism (such as a fungus).
  79. Dual Duct System An air conditioning system that has two ducts, one is heated and the other is cooled, so that air of the correct temperature is provided by mixing varying…
  80. Dual Fuel (or Flex Fuel) Vehicle A vehicle with an engine capable of operating on two different types of fuels.
  81. Dual-fueled (or dual-fired) unit A generating unit that can produce electricity using two or more fuels. In some of these units, only the primary fuel can be used continuously; the…
  82. Duct Fan An axial flow fan mounted in a section of duct to move conditioned air.
  83. Duct(s) The round or rectangular tube(s), generally constructed of sheet metal, fiberglass board, or a flexible plastic-and-wire composite, located within a wall…
  84. Ductility The property of a material that allows it to be formed into thin sections without breaking.
  85. Duff The layer of forest litter.
  86. Dumped A method of compacting soil by dumping the soil into place with no compactive effort.
  87. Dune Mounds of unconsolidated sand grains shaped by wind. Often temporary and nonstationary.
  88. Dunnage Supports for air conditioning and other equipment above the roof of a building.
  89. Duplex DNA Double-stranded DNA.
  90. duplication Multiple occurrence of: 1. A DNA sequence within a defined length of DNA; or 2. A specific segment in the same chromosome or genome.
  91. Duration Curve A cumulative frequency curve that shows the percent of time during which specified units of items (e.g. discharge, head, power, etc.
  92. Duration of Ice Cover The time from freeze-up to break-up of an ice cover.
  93. Duration of Protection Also "Lasting Protection." Site must be established with the intent at the time of designation to provide permanent protection.
  94. Duration of Sunshine The amount of time sunlight was detected at a given point.
  95. DURG During
  96. Duripan A subsurface soil horizon cemented by silica (usually derived from a volcanic source such as ash).
  97. DURN Duration
  98. Dusk Same as Civil Dusk; the time at which the sun is 6 degrees below the horizon in the evening.
  99. Dust Devil A small, rapidly rotating wind that is made visible by the dust, dirt or debris it picks up.
  100. Dust Plume A non-rotating "cloud" of dust raised by straight-line winds. Often seen in a microburst or behind a gust front.