Science — page 68 of 132

13,110 terms including subtopics (0 terms filed directly here)

Subtopics

Science terms

  1. lampbrush chromosome Large diplotene chromosomes present in oocyte nuclei, and particularly conspicuous in amphibians.
  2. Land area Includes dry land and land temporarily or partially covered by water, such as marshlands, swamps, and river flood plains; streams, sloughs, estuaries, and…
  3. Land Breeze A coastal breeze at night blowing from land to sea, caused by the difference in the rates of cooling of their respective surfaces.
  4. Land classification Reclamation's systematic placing of lands into classes based on their suitability for sustained irrigated farming.
  5. Land Conservation and Development Commission (LCDC) (LCDC) In Oregon, a commission appointed to determine land use policy.
  6. Land cover The physical coverage of land, usually expressed in terms of vegetation cover or lack of it.
  7. Land disturbance Discrete event or process that alters soil and/or kills or damages vegetation. From an ecological and hierarchical perspective, disturbance is a change in…
  8. Land disturbance in natural drainage systems Any movement (e.g., grading or excavation) of soil or sediment in a natural drainageway.
  9. Land ownership Land held in title.
  10. Land retirement Permanent removal of land from agricultural production.
  11. Land sky Land sky The relatively dark appearance of the underside of a cloud layer when it is over land that is not snow covered.
  12. Land subsidence The sinking or settling of land to a lower level in response to various natural and man-caused factors.
  13. Land Trusts Nonprofit organizations interested in the protection of natural resources and historic areas.
  14. Land Use The manner in which a parcel of land is used or occupied.
  15. Land Use Board of Appeals (LUBA) (LUBA) In Oregon, a seven-member board appointed to adjudicate land use disputes.
  16. Land Use Plan A set of decisions that establish management direction for land within an administrative area, as prescribed under the planning provisions of FLPMA; an…
  17. Land withdrawal Withdrawals are governed by regulations issued under FLPMA, contained in 43 CFR Part 2300.
  18. Landfall The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely…
  19. Landfill An open area where trash is buried. Facility in which solid waste from municipal and/or industrial sources is disposed; sanitary landfills are those that…
  20. Landfill Gas Methane gas that forms in landfills from the decay of organic materials. The gas can be collected and used for power generation.
  21. Landform Any feature of the Earth's surface having a distinct shape and origin. Landforms include major features (such as continents, ocean basins, plains…
  22. Landholder A landholder is an individual or legal entity owning or leasing land subject to the acreage limitation provisions.
  23. Landing A cleared working area on or near a timber harvest site at which processing steps are carried out.
  24. Landmark Type of reference point external to the observer. Usually a simply defined physical object.
  25. landrace In plant genetic resources, an early, cultivated form of a crop species, evolved from a wild population, and generally composed of a heterogeneous mixture…
  26. Landscape A region consisting of interacting ecosystems determined by geology, soils, climate, biota, and human influences.
  27. Landscape character The arrangement of a particular landscape as formed by the variety and intensity of the landscape features and the four basic elements of form, line…
  28. Landscaping Features and vegetation on the outside of or surrounding a building for aesthetics and energy conservation.
  29. Landslide The failure of a sloped bank of soil or rock in which the movement of the mass takes place along a surface of sliding.
  30. Landspout [Slang], a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone…
  31. Langley A unit or measure of solar radiation; 1 calorie per square centimeter or 3.69 Btu per square foot.
  32. Lapse Rate The rate of change of an atmospheric variable, usually temperature, with height.
  33. LARC (Limited Automatic Report Collector) An electronic device that interfaces a river or precipitation gage with a telephone line making it possible for remote computers to call a gaging site and…
  34. Large Marine Ecosystems Regions of ocean space encompassing coastal areas from the river basins and estuaries out to the seaward boundary and continental shelves and to the…
  35. Large Scale (Synoptic Scale) Size scale referring generally to weather systems with horizontal dimensions of several hundred miles or more.
  36. Large Scale Structure Galaxies, galaxy clusters, and galaxy superclusters.
  37. Large woody debris Dead woody material greater than 20" in diameter on the ground or in a stream or river. It may consist of logs, trees, or parts of trees.
  38. Large-scale atmospheric processes Large-scale atmospheric processes (circulation) Atmospheric processes with a representative scale (large-scale) of 10 000 km.
  39. Larval fish An immature stage that develops from the fertilized egg before assuming the characteristics of the adult.
  40. Last Scattering Surface The farthest back in the history of the universe that photons could travel freely.
  41. Last Update The time and date in which the forecast was issued or updated. The forecast may be updated at any time as weather conditions warrant.
  42. Lasting For purposes of national system natural heritage and cultural heritage MPAs, the site's authority must clearly state its intent to provide permanent…
  43. LAT Latitude- The location north or south in reference to the equator, which is designated at zero (0) degrees.
  44. Late Archaic The period 3,000 to 1,500 years B.P.
  45. Late seral species Shade tolerant species, primarily vine maple shrubs and western red cedar and western hemlock trees.
  46. Late seral treatment A treatment in which late seral species will be established after thinning.
  47. Late-successional forest Forest seral stages which include mature and old- growth age classes.
  48. Late-successional reserve An area of forest where the management objective is to protect and enhance conditions of late successional and old-growth forest ecosystems.
  49. latent agent A pathogen, usually a virus, present in a host organism without producing any symptoms.
  50. latent bud An inactive bud not held back by rest or dormant period, but which may start growth if stimulated.
  51. Latent Cooling Load The load created by moisture in the air, including from outside air infiltration and that from indoor sources such as occupants, plants, cooking…
  52. Latent Heat The change in heat content that occurs with a change in phase and without change in temperature.
  53. Latent Heat Flux The flux of heat from the earth's surface to the atmosphere that is associated with evaporation or condensation of water vapor at the surface; a component…
  54. Latent Heat of Vaporization The quantity of heat produced to change a unit weight of a liquid to vapor with no change in temperature.
  55. latent phase See: lag phase.
  56. Lateral A channel that conveys water from a canal to a farm, municipality, etc.
  57. lateral bud See: axillary bud.
  58. lateral meristem A meristem giving rise to secondary plant tissues, such as the vascular and cork cambia.
  59. Lateral moraine Ridge-like pile of sediment along the side of a glacier.
  60. Latite An igneous, volcanic (extrusive) rock.
  61. Latitude (abbrev. LAT) The location north or south in reference to the equator, which is designated at zero (0) degrees.
  62. Lattice The regular periodic arrangement of atoms or molecules in a crystal of semiconductor material.
  63. Laurentide ice sheet the ice sheet that grew over a large part of North America during the last glacial period.
  64. Lava Magma that reaches the Earth's surface and issues from volcanoes.
  65. Lava flow An outpouring of lava onto the land surface from a vent or fissure. Also, a solidified tongue-like or sheetlike body formed by outpouring lava.
  66. Lava tubes Natural conduits through which lava moves beneath the surface of a lava flow during a volcanic eruption.
  67. Law of the River A complex body of laws, court decrees, contracts, agreements, regulations and an international treaty used to govern allocation and management of Colorado…
  68. Law(s) of Thermodynamics The first law states that energy can not be created or destroyed; the second law states that when a free exchange of heat occurs between two materials…
  69. LAWEB (Great Lakes Weather Broadcast) - A National Weather Service product containing an observation summary prepared to provide Great Lakes mariners with a…
  70. Lawn A uniform and uninterrupted laver of bacterial growth, in which individual colonies cannot be observed.
  71. Laydown area An area that has been cleared for the temporary storage of equipment and supplies.
  72. Layer Composite Reflectivity Average This WSR-88D radar product displays the average reflectivities for a layer. Data is taken from all elevation angles contained in a given layer for each…
  73. Layer Composite Reflectivity Maximum This WSR-88D radar product displays the maximum reflectivities for a layer. Data is taken from all elevation angles contained in a given layer for each…
  74. Layered Haze Haze produced when air pollution from multiple line, area or point sources is transported long distances to form distinguishable layers of discoloration…
  75. layering A technique for vegetative propagation, in which new plants produce adventitious roots before being severed from the parent plant.
  76. LCD (Local Climatological Data) This National Climatic Data Center (NCDC) publication is produced monthly and annually for some 270 United States cities and it's territories.
  77. LCL 1. Abbreviation for "local" or "locally" 2. Lifting Condensation Level - the level at which a parcel of moist air becomes saturated when it is lifted dry…
  78. LCR Abbreviation for ligase chain reaction.
  79. LD50 Abbreviation for lethal dose50%. The amount of a substance required to kill 50% of the test population.
  80. LDS Lightning Detection System
  81. LDT Local Daylight Time.
  82. Leach To remove components from the soil by the action of water trickling through.
  83. Leachate A liquid that results from water collecting contaminants as it trickles through wastes, agricultural pesticides or fertilizers.
  84. Leachates Liquids percolated through waste piles. Leachate can include various minerals, organic matter, or other contaminants and can contaminate surface water or…
  85. Leaching Removal of soluble material from soil or other permeable material by the passage of water through it.
  86. Leaching field (leaching cesspool) A lined or partially lined underground pit into which raw household water (sewage) is discharged and from which the liquid seeps into the surrounding soil.
  87. Leaching requirement Quantity of irrigation water required for transporting salts through the soil profile to maintain a favorable salt balance in the root zone for plant…
  88. Lead A gray-white metal that is listed as a criteria air pollutant. Health effects from exposure to lead include brain and kidney damage and learning…
  89. Lead Acid Battery An electrochemical battery that uses lead and lead oxide for electrodes and sulfuric acid for the electrolyte.
  90. lead compound A chemical that has demonstrated promising biological activity in preliminary assays.
  91. Lead time Time available for Decision Makers to determine if conditions at a dam and reservoir, or in the basin, warrant declaration of a specific emergency…
  92. Leader The streamer which initiates the first phase of each stroke of a lightning discharge.
  93. leader peptide See: signal sequence.
  94. leader sequence A variable length sequence of nucleotides at the 5' end of an mRNA molecule that precedes the AUG initiation codon where translation begins and is not…
  95. Leader Spot In solar-terrestrial terms, in a magnetically bipolar or multipolar sunspot group, the western part precedes and the main spot in that part is called the…
  96. Leadership in Energy and Environmental Design (LEED) (LEED) Green Building Rating System is a nationally accepted benchmark for the design, construction, and operation of high performance green buildings.
  97. Leading Edge In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind.
  98. leading strand The strand of DNA that is synthesized continuously during replication.
  99. leaf blade The usually flattened portion of the leaf.
  100. leaf bud cutting A cutting that includes a short section of stem with attached leaf.