Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: H (128)

• H0On a buoy report, Significant Wave Height is the average height (meters) of the highest one-third of the...
• H5500 millibar level height (in a standard atmosphere this is near 5,500 meters (18,000 ft)
• H7height of the 700 millibar level. In a standard atmosphere this is near 3,000 meters (10,000 ft)
• H8height of the 850 millibar level.
• Hague LineThe North Atlantic boundary between the U.S. and Canada fishing waters as determined by the World Court in...
• hailShowery precipitation in the form of irregular pellets or balls of ice more than 5 mm in diameter, falling...
• Hail ContaminationA limitation in NEXRAD rainfall estimates whereby abnormally high reflectivities associated with hail are...
• Hail IndexAn indication of whether the thunderstorm structure of each storm identified is conducive to the production...
• Hail SizeTypically refers to the diameter of the hailstones. Warnings and reports may report hail size through...
• Hail SpikeAn area of reflectivity extending away from the radar immediately behind a thunderstorm with extremely large...
• Haines indexThis is also called the Lower Atmosphere Stability Index. It is computed from the morning (12Z) soundings...
• haloAny of a variety of bright circles or arcs centered on the sun or moon, caused by the refraction or...
• H-AlphaIn solar-terrestrial terms, this absorption line of neutral hydrogen falls in the red part of the visible...
• Hanging (ice) damIn hydrologic terms, a mass of ice composed mainly of frazil or broken ice deposited underneath an ice cover...
• hard freezeA hard freeze occurs when the surface air temperature reaches 28°F or lower for an extended period of time...
• Hazardous Seas WarningA warning for wave heights and/or wave steepness values meeting or exceeding locally defined warning criteria.
• Hazardous Seas WatchA watch for an increased risk of a hazardous seas warning event to meet Hazardous Seas Warning criteria but...
• Hazardous Weather OutlookA narrative statement produced by the National Weather Service, frequently issued on a routine basis, to...
• Hazards AssessmentCPC's Hazards Assessment provides emergency managers, planners, forecasters and the public advance notice of...
• haze(abbrev. HZ)- An aggregation in the atmosphere of very fine, widely dispersed, solid or liquid particles, or...
• H-component of the Geomagnetic Field(Geomagnetic Elements) In solar-terrestrial terms, the components of the geomagnetic field at the surface of...
• HDDHeating Degree Days- A form of degree day used to estimate energy requirements for heating. Typically...
• HDRAINAn Hourly Digital Rainfall Product of the WSR-88D.
• headIn hydrologic terms, the difference between the pool height and tailwater height. Usually expressed in feet...
• Head LossIn hydrologic terms, the decrease in total head caused by friction
• Head RaceIn hydrologic terms, a channel which directs water to a water wheel; a forebay.
• Headward ErosionIn hydrologic terms, erosion which occurs in the upstream end of the valley of a stream, causing it to...
• Headwater BasinIn hydrologic terms, a basin at the headwaters of a river. All discharge of the river at this point is...
• headwatersIn hydrologic terms, streams at the source of a river.
• Heat AdvisoryThis product is issued for dangerous heat conditions that are not expected to reach warning criteria.
• Heat CrampsPainful, involuntary muscle spasms that can occur due to the overheating of the body during prolonged...
• Heat ExhaustionA heat-related illness characterized by the body's inability to effectively cool itself, typically occurring...
• Heat indexThe Heat Index (HI) or the "Apparent Temperature" is an accurate measure of how hot it really feels when the...
• heat lightningLightning that occurs at a distance such that thunder is no longer audible.
• Heat StrokeA serious heat-related illness where the body can no longer control its temperature: the body's temperature...
• heat waveA period of abnormally and uncomfortably hot and unusually humid weather. Typically a heat wave lasts two or...
• Heating Degree Days(abbrev. HDD) A form of degree day used to estimate energy requirements for heating. Typically, heating...
• HeatRiskA color-numeric-based index that uses weather, climate, and Centers for Disease Control and Prevention (CDC)...
• Heavy Freezing SprayAn accumulation of freezing water droplets on a vessel at a rate of two cm per hour or greater (0.7 cm per...
• Heavy Freezing Spray WarningA warning for an accumulation of freezing water droplets on a vessel at a rate of two cm per hour or greater...
• Heavy Freezing Spray WatchA watch for an increased risk of a heavy freezing spray event to meet Heavy Freezing Spray Warning criteria...
• Heavy SnowThis generally means...
• Heavy Snow WarningIssued by the National Weather Service when snowfall of 6 inches (15 cm) or more in 12 hours or 8 inches (20...
• Heavy Surf AdvisoryAn advisory issued by the National Weather Service for fast moving deep water waves which can result in big...
• hectopascalA unit of pressure equal to a millibar (1 hPa = 1 mb). Abbreviated hPa.
• HeightIn meteorology, usually a reference to Geopotential Height; roughly the height above sea level of a pressure...
• Height Above the Nearest DrainageA relative elevation methodology used in inundation mapping, which determines the height of every point on a...
• helicityA property of a moving fluid which represents the potential for helical flow (i.e. flow which follows the...
• hertz(abbrev. Hz)- An international unit of frequency equal to one cycle per second, and named after a German...
• HIHigh- In meteorology, a region of high pressure; also known as anticyclone.
• HICHydrologist In Charge
• high(abbrev. HI)- In meteorology, a region of high pressure; also known as anticyclone.
• High CloudsThese clouds have bases between 16,500 and 45,000 feet in the mid latitudes. At this level they are composed...
• High Energy EventIn solar-terrestrial terms, flares (class two or more) with outstanding Centimetric Bursts and SID. High...
• High Flow MagnitudeThe magnitude of the maximum forecast streamflow conditions, measured in terms of annual exceedance...
• high frequencyThe portion of the radio frequency spectrum between between 3 and 30 MHz
• High LatitudesWith specific reference to zones of geomagnetic activity, "high latitudes" refers to 50º to 80º geomagnetic.
• High Resolution Ensemble ForecastAn ensemble of products from several different models running at ~3 km horizontal grid spacing.
• High Resolution Rapid RefreshA real-time 3-km resolution, hourly updated, cloud-resolving, convection-allowing atmospheric model...
• High Risk (of severe thunderstorms)Severe weather is expected to affect more than 10 percent of the area. A high risk is rare, and implies an...
• High Seas Forecast(HSF) - Marine forecasts for the major oceans of the world. In this context, major gulfs or seas (e.g., the...
• High SurfLarge waves breaking on or near the shore resulting from swells spawned by a distant storm.
• High Surf AdvisoryA High Surf Advisory is issued when breaking wave action poses a threat to life and property within the surf...
• High Surf WarningA High Surf Warning is issued when breaking wave action results in an especially heightened threat to life...
• High Water Arrival TimeThe time at which a stream reach is forecast to achieve its high water flow within the forecast period.
• High Water FlowThe Office of Water Prediction (OWP) uses the term “high water” as an indicator of elevated flows for a given...
• High Water ProbabilityThe probability (%) that a stream will reach its high water flow within the forecast period.
• High WindSustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or winds of 58 mph or greater for...
• High Wind WarningThis product is issued when sustained, strong winds with even stronger gusts are expected or occurring...
• High Wind WatchThis product is issued when a high wind event is possible, but its occurrence, location, and/or timing is...
• High-Speed StreamIn solar-terrestrial terms, a feature of the solar wind having velocities that are about double average solar...
• Hinge CrackIn hydrologic terms, a crack caused by significant changes in water level.
• HLSHurricane Local Statement
• HMD(Hemispheric Map Discussion)- This discussion is issued once a day around 1 PM EST (2 PM EDT) and is...
• HNDHundred
• Hoar FrostA deposit of interlocking crystals formed by direct sublimation on objects, usually those of small diameter...
• hodographA polar coordinate graph which shows the vertical wind profile of the lowest 7000 meters of the atmosphere...
• Homologous FlaresIn solar-terrestrial terms, solar flares that occur repetitively in the same active region, with essentially...
• hook echoA radar reflectivity pattern characterized by a hook-shaped extension of a thunderstorm echo, usually in the...
• horizonThe distant line along which the earth and sky appear to meet. Obstructions are not considered as part of the...
• Hourly Precipitation DataIt contains data on nearly 3,000 hourly precipitation stations (National Weather Service, Federal Aviation...
• HP Stormor HP Supercell - High-Precipitation storm (or High-Precipitation supercell). A supercell thunderstorm in...
• hPaHectopascal- A unit of pressure equal to a millibar (1 hPa = 1 mb).
• HPCHydrometeorological Prediction Center
• HRHour
• HRShours
• HSA (Hydrologic Service Area)A geographical area assigned to Weather Service Forecast Office's/Weather Forecast Office's that embraces one...
• humidityGenerally, a measure of the water vapor content of the air. Popularly, it is used synonymously with relative...
• Humidity RecoveryThe change in relative humidity over a given period of time; generally between late evening and sunrise. The...
• hummockIn hydrologic terms, a hillock of broken ice which has been forced upward by pressure
• hummocked iceIn hydrologic terms, ice piled haphazardly one piece over another to form an uneven surface.
• hurricane(abbrev. HURCN) A tropical cyclone in the Atlantic, Caribbean Sea, Gulf of Mexico, or eastern Pacific, which...
• Hurricane Force Wind WarningA warning for sustained winds, or frequent gusts, of 64 knots (74 mph) or greater, either predicted or...
• Hurricane Force Wind WatchA watch for an increased risk of a hurricane force wind event for sustained surface winds, or frequent gusts...
• Hurricane Local StatementA public release prepared by local National Weather Service offices in or near a threatened area giving...
• Hurricane SeasonThe part of the year having a relatively high incidence of tropical cyclones. In the Atlantic, Caribbean, and...
• hurricane warningAn announcement that hurricane conditions (sustained winds of 74 mph or higher) are expected somewhere within...
• hurricane watchAn announcement that hurricane conditions (sustained winds of 74 mph or higher) are possible within the...
• HVhave
• HVYHeavy
• HWRFNWS/Hurricane Weather Research and Forecasting Model
• HWVRHowever
• Hyder FlareIn solar-terrestrial terms, a filiment-associated two-ribbon flare, often occurring in spotless regions. The...
• Hydraulic Fill DamIn hydrologic terms, a dam constructed of materials, often dredged, that are conveyed and placed by...
• Hydraulic FlowAtmospheric flow that is similar in character to the flow of water over an obstacle.
• hydraulic grade lineIn hydrologic terms, a line whose plotted ordinate position represents the sum of pressure head plus...
• hydraulic headIn hydrologic terms, (1) The height of the free surface of a body of water above a given point beneath the...
• hydraulic jumpA steady disturbance in the lee of a mountain, where the airflow passing over the mountain suddenly changes...
• Hydraulic PermeabilityIn hydrologic terms, the flow of water through a unit cross-sectional area of soil normal to the direction of...
• hydrographIn hydrologic terms, a graph showing the water level (stage), discharge, or other property of a river volume...
• Hydrograph SeparationIn hydrologic terms, the process where the storm hydrograph is separated into baseflow components and surface...
• Hydrographic SurveyIn hydrologic terms, an instrumental survey to measure and determine characteristics of streams and other...
• Hydrologic BudgetIn hydrologic terms, an accounting of the inflow to, outflow from, and storage in, a hydrologic unit, such as...
• hydrologic cycleThe description of the transport of water substance between the earth, the atmosphere, and the seas.
• Hydrologic Ensemble Forecast SystemA probabilistic forecast tool with the goals to provide hydrologic forecasts including an analysis of...
• hydrologic equationIn hydrologic terms, the water inventory equation (Inflow = Outflow + Change in Storage) which expresses the...
• Hydrologic ModelIn hydrologic terms, a conceptual or physically-based procedure for numerically simulating a process or...
• Hydrologic Service AreaHSA. A geographical area assigned to Weather Service Forecast Office's/Weather Forecast Office's that...
• hydrologyThe scientific study of the waters of the earth, especially with relation to the effects of precipitation and...
• hydrometeorA particle of condensed water (liquid, snow, ice, graupel, hail) in the atmosphere.
• HydrometeorologistsIn hydrologic terms, individuals who have the combined knowledge in the fields of both meteorology and...
• hydrometeorologyAn interdisciplinary science involving the study and analysis of the interrelationships between the...
• Hydrostatic HeadIn hydrologic terms, a measure of pressure at a given point in a liquid in terms of the vertical height of a...
• hyetographA graphical representation of rainfall intensity with respect to time.
• hygrometerAn instrument which measures the humidity of the air.
• hygroscopicAbsorbing or attracting moisture from the air.
• hypothermiaA rapid, progressive mental and physical collapse that accompanies the lowering of body temperature.
• HZ1) Haze- An aggregation in the atmosphere of very fine, widely dispersed, solid or liquid particles, or both...

128 of 3,164 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.