Science terms starting with L

480 terms

  1. Loose Fill Insulation Insulation made from rockwool fibers, fiberglass, cellulose fiber, vermiculite or perlite minerals, and composed of loose fibers or granules can be…
  2. Loose yards Measurement of soil or rock after it has been loosened by digging or blasting.
  3. LOPRES low pressure
  4. Loran Long Range Navigation, a system of long range navigation whereby latitude and longitude are determined from the time displacement of radio signals from…
  5. Losing stream A stream or reach that contributes water to a zone of saturation.
  6. Loss of Load Probability (LOLP) A measure of the probability that a system demand will exceed capacity during a given period; often expressed as the estimated number of days over a long…
  7. Losses Energy (kilowatt-hours) and power (kilowatts) lost in the operation of an electric system, principally as waste heat in electrical conductors and…
  8. Losses (Energy) A general term applied to the energy that is converted to a form that can not be effectively used (lost) during the operation of an energy producing…
  9. Lot Area area is the total square footage of horizontal area included within the property lines.
  10. Lotic Moving water systems such as streams and rivers.
  11. Lotic System A flowing body of fresh water, such as a river or stream. Compare lentic system.
  12. Low A region of low pressure, marked as "L" on a weather map. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds.
  13. Low Btu Gas A fuel gas with a heating value between 90 and 200 Btu per cubic foot.
  14. Low dam A dam up to 100 feet high. See medium-height dam and high dam.
  15. Low density material A material having a low weight per unit volume either as it occurs in its natural state or after compacting it, such as loess with a density of 80 pounds…
  16. Low Emission Vehicle (LEV) A vehicle meeting the low-emission vehicle standards.
  17. Low Flush Toilet A toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources.
  18. Low Frequency (abbrev. LF) The portion of the radio frequency spectrum from 30 to 300 kHz.
  19. Low hazard A downstream hazard classification for dams in which no lives are in jeopardy and minimal economic loss (undeveloped agriculture, occasional uninhabited…
  20. Low Impact Development (LID) An approach to environmentally friendly land use planning. It includes a suite of landscaping and design techniques that attempt to maintain the natural…
  21. Low Level Jet (abbrev. LLJ)- A region of relatively strong winds in the lower part of the atmosphere.
  22. Low Pressure System An area of a relative pressure minimum that has converging winds and rotates in the same direction as the earth.
  23. Low-E Coatings & (Window) Films A coating applied to the surface of the glazing of a window to reduce heat transfer through the window.
  24. Low-e windows Low-emittance (Low-E) refers to very thin coatings on a window primarily used to reduce heat flow through the window.
  25. Low-Emissivity Windows & (Window) Films Energy-efficient windows that have a coating or film applied to the surface of the glass to reduce heat transfer through the window.
  26. Low-Flow Solar Water Heating Systems The flow rate in these systems is 1/8 to 1/5 the rate of most solar water heating systems.
  27. Low-head hydroelectric Hydroelectric power that operates with a head of 20 meters (approximately 66 feet) or less.
  28. Low-income population Persons whose average family income is below the poverty line. The poverty line takes into account family size and age of individuals in the family.
  29. Low-level clouds Low-level clouds (St, Sc, Ns) Stratus, Stratocumulus, and in some degree, Nimbostratus are low clouds.
  30. Low-level magnetic fields Fields of force that are generated whenever electric current flows. The sun's average large-scale magnetic field, and the Earth's, exhibit a north and a…
  31. Low-Level Outlet (Drain, Bottom Outlet or Sluiceway) An opening at a low level from a reservoir generally used for emptying or for scouring sediment and sometimes for irrigation releases.
  32. Low-Pressure Sodium Lamp A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal.
  33. Lower (Net) Heating Value The lower or net heat of combustion for a fuel that assumes that all products of combustion are in a gaseous state. (See Net Heating Value below.)
  34. Lower heating value Quantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water remains as a vapor and the…
  35. Lower Heating Value (LHV) The heating value is the amount of heat released during the combustion of a specific substance, usually a fuel or food.
  36. lower heating value (LLV) The heat produced by combusting one unit of a substance, at atmospheric pressure under conditions such that all water in the products remains in the form…
  37. Lowest achievable emissions rate (LAER) Used to describe air emissions control technology. A rate of emissions defined by the permitting agency.
  38. Lowland Flooding Inundation of low areas near the river, often rural, but may also occur in urban areas.
  39. LP Storm Low-Precipitation storm (or Low-Precipitation supercell). A supercell thunderstorm characterized by a relative lack of visible precipitation.
  40. LPS Abbreviation for lipopolysaccharide.
  41. LRG Large
  42. LSR Local Storm Report. A product issued by local NWS offices to inform users of reports of severe and/or significant weather-related events
  43. LST Local Standard Time
  44. LTD Limited
  45. LTL Little
  46. LTLCG Little Change
  47. LTNG Lightning- A visible electrical discharge produced by a thunderstorm. The discharge may occur within or between clouds, between the cloud and air, between…
  48. LTR Abbreviation for long terminal repeat.
  49. LTST latest
  50. Lubricant (LOO-brih-kant) An oily or slippery substance.
  51. Lumen The cavity or channel within a tube or tubular organ such as a blood vessel or the intestine.
  52. Lumens/Watt (lpw) A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the lamp for each unit of electrical power (Watts)…
  53. Luminaire A complete lighting unit consisting of a lamp(s), housing, and connection to the power circuit.
  54. Luminance The physical measure of the subjective sensation of brightness; measured in lumens.
  55. Luminosity The total energy released by an object emitting light, (in our case, this will be a star) per unit time (usually per second).
  56. luteinizing hormone A pituitary hormone which causes growth of the yellow body of the ovary and also stimulates activity of the interstitial cells of the testis.
  57. Lux The unit of illuminance equivalent to 1lumen per square meter.
  58. luxury consumption Nutrient absorption by an organism in excess of that required for optimum growth and productivity.
  59. LVL Level
  60. LVLS levels
  61. LWR Lower
  62. lyase Any of a class of enzymes that catalyse either the cleavage of a double bond and the addition of new groups to a substrate, or the formation of a double…
  63. Lymph Node A small rounded or bean-shaped mass of lymphatic tissue that helps the body's immune system.
  64. Lymph nodes (LIMF nohdz): Small glands that help the body fight infection and disease. They filter a fluid called lymph and contain white blood cells.
  65. Lymphatic system (lim-FA-tik SIS-tem) The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases.
  66. Lymphocyte (LIM-foh-site) A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other…
  67. Lymphoid (LIM-foyd) Referring to lymphocytes, a type of white blood cell. Also refers to tissue in which lymphocytes develop.
  68. lymphokine Generic name for proteins that are released by lymphocyte s to act on other cells involved in the immune response.
  69. lymphoma (lim-FOH-muh) Cancer that begins in cells of the immune system. There are two basic categories of lymphomas.
  70. lyophilize See: freeze-dry ing.
  71. Lysimeter An isolated block of soil, usually undisturbed and in situ, for measuring the quantity, quality, or rate of water movement through or from the soil.
  72. lysis (LY-sis) In biology, lysis refers to the breakdown of a cell caused by damage to its plasma (outer) membrane.
  73. Lysogen A bacterial cell whose chromosome contains in- tegrated viral DNA.
  74. lysogenic Bacteria or bacteriophages undergoing lysogeny.
  75. lysogenic bacterium Bacterium harbouring temperate (non-virulent, lysogenic ) bacteriophages.
  76. lysogeny A condition in which a bacteriophage genome (pro-phage ) survives within a host bacterium, either as part of the host chromosome or as part of an…
  77. lysosome A sac-like compartment inside a cell that has enzymes that can break down cellular components that need to be destroyed.
  78. lysozyme A naturally occurring enzyme extracted from egg white protein and other animal and plant sources, which attacks the cell wall of gram-positive bacteria…
  79. lytic Having to do with lysis. In biology, lysis refers to the disintegration of a cell by disruption of its plasma membrane.
  80. lytic cycle The steps in viral production that lead to cell lysis.