ExpertGlossary terms starting with H

1,452 terms

  1. Hydrogen A chemical element that can be used as a fuel since it has a very high energy content.
  2. Hydrogen bond A relatively weak bond formed between a hydrogen atom (which is covalently bound to a nitrogen or oxygen atom) and a nitrogen or oxygen with an unshared…
  3. hydrogen peroxide A chemical used in bleaches, dyes, cleansers, antiseptics, and disinfectants. In a concentrated form, it is toxic and irritating to tissues.
  4. hydrogen-uptake positive (Abbreviation: Hup+). A term describing a micro-organism that is capable of assimilating (or taking up) hydrogen gas.
  5. Hydrogenated Amorphous Silicon Amorphous silicon with a small amount of incorporated hydrogen. The hydrogen neutralizes dangling bonds in the amorphous silicon, allowing charge carriers…
  6. hydrogenation Treatment of substances with hydrogen and suitable catalysts at high temperature and pressure to saturate double bonds.
  7. Hydrogeochemistry Chemistry of ground water and surface water.
  8. Hydrogeologic conditions Conditions stemming from the interaction of ground water and the surrounding soil and rock.
  9. Hydrogeologic cycle The natural process of recycling water from the atmosphere down to (and through) the earth and back to the atmosphere again.
  10. Hydrogeologist A person who studies and works with ground water.
  11. Hydrogeology The geology of ground water, with particular emphasis on the chemistry and movement of water.
  12. Hydrograph A graphical representation of the stage or discharge as a function of time at a particular point on a watercourse; a time-discharge curve of the unsteady…
  13. Hydrograph Separation The process where the storm hydrograph is separated into baseflow components and surface runoff components.
  14. Hydrographic Survey An instrumental survey to measure and determine characteristics of streams and other bodies of water within an area, including such things as location…
  15. Hydrography Scientific study of physical aspects of all waters on the Earth's surface. Water features in 7.
  16. Hydrologic Budget An accounting of the inflow to, outflow from, and storage in, a hydrologic unit, such as a drainage basin, aquifer, soil zone, lake, reservoir, or…
  17. Hydrologic Cycle Cycle of water movement from atmosphere to Earth by precipitation and its return to the atmosphere by interception, evaporation, runoff, infiltration…
  18. hydrologic cycle (or water cycle) the combined fluxes of water occurring on, above, and below the surface of the earth.
  19. Hydrologic Equation The water inventory equation (Inflow = Outflow + Change in Storage) which expresses the basic principle that during a given time interval the total inflow…
  20. Hydrologic Model A conceptual or physically-based procedure for numerically simulating a process or processes which occur in a watershed.
  21. Hydrologic Operations Division (HOD) The Hydrologic Operations Division of the Office of Hydrology (OH).
  22. Hydrologic Service Area HSA. A geographical area assigned to Weather Service Forecast Office's/Weather Forecast Office's that embraces one or more rivers.
  23. Hydrologic Service Area (HSA) A geographical area assigned to Weather Service Forecast Office's/Weather Forecast Office's that embraces one or more rivers.
  24. Hydrologic Services A general term referring to the operations, products, verbal communications, and related forms of support provided by the NWS for the Nation's streams…
  25. Hydrologic Systems Branch (HSB) The Hydrologic Systems Branch in the Office of Hydrology (OH).
  26. Hydrologic Unit A geographical area representing part or all of a surface drainage basin or distinct hydrologic feature such as a reservoir, lake, etc.
  27. Hydrologic unit code An eight-digit number used to identify a geographic area representing part or all of a surface drainage basin or distinct hydrologic feature.
  28. Hydrological Research Laboratory (HRL) The Hydrological Research Laboratory at the Office of Hydrology (OH).
  29. Hydrologist on Duty (HOD) The Hydrologist on Duty at an RFC.
  30. Hydrologists Individuals who study the applied science of hydrology and solve hydrologic problems.
  31. Hydrology The science dealing with the distribution, properties and circulation of water on land, in the soil, and in the atmosphere.
  32. Hydrolysis A chemical reaction that uses water to break down a compound.
  33. Hydromet A system of data collection platforms that gathers hydrometeorological data, and transmits that data via GOES Satelite to a computer downlink.
  34. Hydrometeor A particle of condensed water (liquid, snow, ice, graupel, hail) in the atmosphere.
  35. hydrometeor types Information that delineates hydrometeors into such microphysical classes as rain, snow, graupel, and hail.
  36. Hydrometeorological Automated Data System (HADS) Software that replaced GDDS to process and distribute the GOES DCP data and CADAS data collected from DCP's and LARCS.
  37. Hydrometeorological Information Center (HIC) The Hydrometeorological Information Center of the Office of Hydrology (OH).
  38. Hydrometeorological Report (HMR) A series of hydrometeorological reports published by the National Weather Service (NWS) addressing meteorological issues related mainly to developing…
  39. Hydrometeorological Technicians Individuals whose duties include data collection, quality control, gage network maintenance, as well as the gathering and disseminating of data and…
  40. Hydrometeorologists In hydrologic terms, individuals who have the combined knowledge in the fields of both meteorology and hydrology which enables them to study and solve…
  41. Hydrometeorology An inter­disci­plinary science involving the study and analysis of the inter­relation­ships between the atmo­spheric and land phases of…
  42. Hydrometer A device for measuring the specific gravity of fluids.
  43. hydromorphone A drug used to relieve pain.
  44. hydronephrosis Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine…
  45. Hydronic Heating Systems A type of heating system where water is heated in a boiler and either moves by natural convection or is pumped to heat exchangers or radiators in rooms…
  46. Hydrophilic Having a strong affinity (liking) for water. The opposite of hydrophobic.
  47. Hydrophobic Having a strong aversion (dislike) for water. The opposite of hydrophilic.
  48. hydrophobic interaction An interaction between a hydrophobic ('water-hating') part of a molecule and an aqueous environment.
  49. hydroponics The growing of plants without soil. Plants are fed with an aerated solution of nutrients, and the roots are either supported within an inert matrix, or…
  50. Hydropower The force of flowing water moving downstream creates energy that can be harnessed and turned into electricity.
  51. Hydrosphere The region that includes all the earth's liquid water, frozen water, floating ice, frozen upper layer of soil, and the small amounts of water vapor in the…
  52. Hydrostatic Relating to pressure or equilibrium of fluids. The pressures and forces resulting from the weight of a fluid at rest.
  53. Hydrostatic Head A measure of pressure at a given point in a liquid in terms of the vertical height of a column of the same liquid which would produce the same pressure.
  54. Hydrostratigraphic Grouping of rock and sedimentary units based on the capacity of the rock, sediment, or soil to transmit water.
  55. Hydrothermal fluids These fluids can be either water or steam trapped in fractured or porous rocks; they are found from several hundred feet to several miles below the…
  56. hydroureter (HY-droh-YER-eh-ter) Abnormal enlargement of the ureter caused by any blockage that prevents urine from draining into the bladder.
  57. Hydroxyapatite A natural mineral structure that contains calcium and phosphate ions that provide the power for the formation of bones and teeth.
  58. hydroxychloroquine A substance that decreases immune responses in the body. It is used to treat some autoimmune diseases, and is being studied as a treatment for…
  59. hydroxyl ion absorption In optical fibers, the absorption of electromagnetic waves, including the near-infrared, due to the presence of trapped hydroxyl ions remaining from water…
  60. hydroxymethylglutaryl-coenzyme A reductase inhibitor (hy-DROK-see-MEH-thul-GLOO-tuh-ril koh-EN-zime-A ree-DUK-tayz in-HIH-bih-ter) A substance that blocks an enzyme needed by the body to make cholesterol and…
  61. hydroxyurea An anticancer drug that belongs to the family of drugs called antimetabolites.
  62. Hydro­meteorology An inter­disci­plinary science involving the study and analysis of the inter­relation­ships between the atmo­spheric and land phases of…
  63. Hyetograph A graphical representation of rainfall intensity with respect to time.
  64. Hygiene (HY-jeen) The science of health, and the practice of cleanliness that promotes good health and well-being.
  65. Hygrometer An instrument which measures the humidity of the air.
  66. hygromycin An antibiotic used as selective agent in bacterial and transgenic plant cell cultures.
  67. Hygroscopic Absorbing or attracting moisture from the air.
  68. hygroscopic growth The rate that aerosol particles grow at relative humidity values less than 100 percent.
  69. HYLYE Hypersonic Low Temperature.
  70. Hyper-Threading A processor architecture feature that allows a single processor to execute multiple independent threads simultaneously.
  71. hyperactivity (HY-per-ak-TIV-ih-tee) A higher than normal level of activity. Hyperactivity can be used to describe the increased action of a body function, such as…
  72. hyperalimentation (HY-per-AL-ih-men-TAY-shun) A form of nutrition that is delivered into a vein. Hyperalimentation does not use the digestive system.
  73. hyperbaric oxygen (HY-per-BAYR-ik OK-sih-jen) Oxygen that is at an atmospheric pressure higher than the pressure at sea level.
  74. hypercalcemia (HY-per-kal-SEE-mee-uh) Higher than normal levels of calcium in the blood. Some types of cancer increase the risk of hypercalcemia.
  75. Hyperconcentrated flow Moving mixture of sediment and water between 40 and 80 percent water by volume.
  76. hyperfractionated radiation therapy (HY-per-FRAK-shuh-NAYT-ed RAY-dee-AY-shun THAYR-uh-pee) Radiation therapy that gives smaller doses (fractions) of radiation more often than standard…
  77. hyperfractionation (hy-per-FRAK-shun-AY-shun) Radiation therapy that gives smaller doses (fractions) of radiation more often than standard radiation therapy so that the full…
  78. hyperglycemia (HY-per-gly-SEE-mee-uh) Higher than normal amount of glucose (a type of sugar) in the blood. Hyperglycemia can be a sign of diabetes or other conditions.
  79. Hyperglycemic Episode or Reation Slow onset of severe elevation in blood glucose levels causing acute complications including stupor, lethargy, blurred vision, disorientation, slow…
  80. Hypericum perforatum (hy-PAYR-ih-kum per-fuh-RAY-tum) An herbal product sold as an over-the-counter treatment for depression.
  81. Hyperinsulinism (Hyperinsulinemia) Increased levels of insulin in the plasma due to increased secretion of insulin by the beta cells (cells that make insulin) of the…
  82. hyperkeratosis (HY-per-KAYR-uh-TOH-sis) A condition marked by thickening of the outer layer of the skin, which is made of keratin (a tough, protective protein).
  83. hyperlink A link - usually appearing as a highlighted word or picture within a hypertext document - that when clicked changes the active view, possibly to another…
  84. Hyperlinks see "links"
  85. Hyperlipidemia (Lipemia) The presence of an abnormally large amount of lipids (fats) in the circulating blood.
  86. hypermedia Computer-addressable files that contain pointers for linking to multimedia information, such as text, graphics, video, or audio in the same or other…
  87. hypernephroma (HY-per-neh-FROH-muh) The most common type of kidney cancer. It begins in the lining of the renal tubules in the kidney.
  88. Hyperparathyroidism (HY-per-PAYR-uh-THY-roy-dih-zum) A condition in which the parathyroid gland (one of four pea-sized organs found on the thyroid) makes too much parathyroid…
  89. Hyperplasia (HY-per-PLAY-zhuh) An abnormal increase in the number of cells in an organ or tissue.
  90. hyperploid The situation in which a particular chromosome or chromosome segment is present in more than the normal number. Opposite: hypoploid.
  91. hypersensitive response 1. A specific reaction of a plant to attack by a pathogen. The plant cells surrounding the point of infection rapidly die and dry out, so that pathogen…
  92. hypersensitive site Regions in the DNA that are highly susceptible to digestion with restriction endonucleases.
  93. hypersensitivity (HY-per-SEN-sih-tih-vih-tee) An exaggerated response by the immune system to a drug or other substance.
  94. Hypertension (HY-per-TEN-shun) A blood pressure of 140/90 or higher. Hypertension usually has no symptoms.
  95. Hypertension Admissions Hypertension is high blood pressure. Having high blood pressure raises your risk for heart disease and stroke, the first and third leading causes of death…
  96. HyperText Text that includes links or shortcuts to other documents or views, allowing the reader to easily jump from one view to a related view in a non-linear…
  97. HyperText Markup Language The HyperText Markup Language (HTML) is a simple presentation language used to markup the content of Web pages.
  98. Hypertext Transfer Protocol See yyHTTP.
  99. hyperthermia (HY-per-THER-mee-uh) Abnormally high body temperature. This may be caused as part of treatment, by an infection, or by exposure to heat.
  100. hyperthermia therapy (HY-per-THER-mee-uh THAYR-uh-pee) A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make…