This list includes 95 Earth science words that start with H, from “Haboob” to “Hypsometry”. These terms describe landforms, processes, measurements, and hazards used in teaching, fieldwork, and public communication.
Earth science words that start with H are specialized terms for natural processes, landforms, materials, and measurement methods. For example, “haboob” comes from Arabic and names intense dust storms in desert regions.
Below you’ll find the table with Term, Definition, Category, Example, and Further reading.
Term: The main word or phrase for each entry; you can scan and sort it to locate terms quickly.
Definition: A concise explanation of the term in one or two sentences; you use it to grasp the core meaning.
Category: Broad grouping like “atmosphere” or “geology”; you can filter the list by topic or curriculum area.
Example: Shows a short real-world instance or context; you can connect each term to familiar events or places.
Further reading: Links to authoritative articles or glossaries for deeper study; you follow them for details or classroom resources.
Earth science words that start with H
| Term | Category | Common units/typical measures | Related concepts |
|---|---|---|---|
| Hydrology | hydrology | m³/s, mm, m³ | Water cycle, runoff, groundwater |
| Hydrosphere | sphere | m³, % Earth surface, km³ | Oceans, cryosphere, atmosphere |
| Hydrologic cycle | process | mm, m³/s, years | Evaporation, precipitation, runoff |
| Hydrograph | method | m³/s, time | Discharge, peak flow |
| Hydrogeology | method | m, m/day, m³/s | Aquifer, groundwater, permeability |
| Hydraulic conductivity | hydrology | m/day, m/s | Permeability, porosity |
| Headwaters | landform | m elevation, km² | Source, watershed, stream |
| Headland | landform | m, km shoreline | Coast, cliff, bay |
| Headwall | landform | m, slope° | Cirque, glacier, scarp |
| Headscarp | landform | m, slope° | Landslide, scarp, mass wasting |
| Heat | process | °C, J, W/m² | Temperature, heat flux, energy budget |
| Heat capacity | property | J/kg·K, J/mol·K | Specific heat, temperature change |
| Heat flux | process | W/m² | Heat flow, geothermal gradient |
| Heat flow | process | mW/m² | Geothermal gradient, mantle heat |
| Heat island | climate | °C difference | Urban, albedo, land use |
| Heat index | climate | °C | Humidity, temperature, human comfort |
| Heat sink | concept | W, J | Ocean, atmosphere, ice |
| Heat wave | hazard | days, °C anomalies | Temperature anomaly, drought |
| Hail | atmosphere | mm, g, m/s | Thunderstorm, updraft, precipitation |
| Haboob | atmosphere | m/s, km visibility | Dust storm, convective outflow |
| Haze | atmosphere | km visibility, µg/m³ | Aerosols, pollution, scattering |
| Halo | atmosphere | ° halo radius | Ice crystals, cirrostratus |
| Hurricane | hazard | km/h, m, hPa | Tropical cyclone, storm surge |
| Hadean | geologic time | Ga (billions years) | Archean, Earth formation |
| Halite | rock/mineral | g/cm³, Mohs hardness | Rock salt, evaporite, NaCl |
| Halocline | oceanography | PSU, salinity gradient | Pycnocline, thermocline, stratification |
| Halogenated? (excluded) | n/a | n/a | n/a |
| Harmattan (wind) | atmosphere | km/h, visibility | Dry wind, dust, Sahara |
| Harmful algal bloom | oceanography | cells/mL, toxin µg/L | Eutrophication, hypoxia |
| Hartebeest? (excluded) | n/a | n/a | n/a |
| Harness? (excluded) | n/a | n/a | n/a |
| Harbor | landform | m depth, km² | Port, bay, estuary |
| Hardness | rock/mineral | Mohs scale, GPa | Mineral strength, abrasion |
| Harmonic tide | oceanography | m, hours | Tidal constituent, tidal analysis |
| Harsh? (excluded) | n/a | n/a | n/a |
| Hartz? (excluded) | n/a | n/a | n/a |
| Haze layer? covered by Haze entry | n/a | n/a | n/a |
| Headland cliff? covered by Headland | n/a | n/a | n/a |
| Hjulström curve | method | m grain size, m/s | Sediment transport, critical velocity |
| High (atmospheric high) | atmosphere | hPa, km | Anticyclone, ridge, fair weather |
| Hill | landform | m elevation | Slope, ridge, knob |
| Hinge fault? (specialist) | landform | m, km | Fold, fault, flexure |
| Horsetail? (excluded) | n/a | n/a | n/a |
| Horn | landform | m elevation | Pyramidal peak, cirque, glaciation |
| Horst | landform | m, km | Graben, fault block, rift |
| Horizon | soil | cm depth, horizon code | Soil layer, soil profile |
| Humus | soil | % organic matter, g/kg | Soil organic matter, peat |
| Humidity | atmosphere | % relative humidity, g/kg specific | Dew point, vapor pressure, condensation |
| Hygrometer | instrument | % RH, °C | Humidity measurement, psychrometer |
| Hydrometer | instrument | g/cm³, specific gravity | Density, salinity, salinometer |
| Hydrophone | instrument | Hz, Pa | Underwater sound, sonar, acoustics |
| Hydrothermal vent | oceanography | °C, m depth | Black smoker, chemosynthesis, mid-ocean ridge |
| Hydrothermal alteration | process | mineral assemblage, °C | Metasomatism, ore deposits |
| Hydrate | rock/mineral | g/cm³, MPa, °C | Gas hydrate, clathrate, methane |
| Hydrocarbon | resource | m³, bbl, ppm | Oil, natural gas, petroleum |
| Hydrocarbon seep | oceanography | m³/day, seeps/km² | Methane, cold seep, chemosynthetic ecosystem |
| Hydrostatic pressure | oceanography | Pa, MPa, bar | Depth, density, buoyancy |
| Hydrography | oceanography | m bathymetry, °C, salinity | Nautical charts, seafloor mapping |
| Hydroplaning? (transport) excluded | n/a | n/a | n/a |
| Hydrosphere coupling? covered by Hydrosphere | n/a | n/a | n/a |
| Hydraulic jump | process | m, m/s, Froude number | Open channel flow, energy dissipation |
| Hydraulic conductivity | hydrology | m/s, m/day | Permeability, transmissivity |
| Hydraulic fracturing | method | MPa, L of fluid | Fracking, induced seismicity, permeability |
| Hydraulic gradient | hydrology | m/m | Darcy’s law, head difference |
| Hydrological modeling | method | m³/s, mm | Watershed models, forecasting, FEMA |
| Hydroclimate | climate | mm/year, °C | Precipitation patterns, drought, variability |
| Hydrologic unit | hydrology | km², basin code | Watershed, catchment, basin |
| Hydrothermal plume | oceanography | °C anomaly, particle mg/L | Vent plume, buoyant plume, dispersal |
| Hypsometry | method | map | Elevation distribution, hypsometric curve |
| Hypsometric curve | method | % area vs elevation | Hypsometry, basin evolution |
| Hypsometric integral | method | unitless | Elevation distribution, uplift/erosion |
| Hjulström curve | method | m grain size, m/s velocity | Sediment transport, erosion threshold |
| Hypocenter | hazard | km depth, moment magnitude | Focus, epicenter, earthquake |
| Hypocenter depth | hazard | km | Seismic depth, shallow/deep |
| Hypolimnion | limnology | °C, m depth, mg/L O₂ | Thermocline, epilimnion, stratification |
| Holocene | geologic time | ka (thousands years) | Pleistocene, Anthropocene, climate change |
| Holomictic lake | limnology | mixing period, °C | Mixing, stratification, monomictic |
| Hominin? (excluded biological) | n/a | n/a | n/a |
| Hornfels | rock/mineral | g/cm³, Mohs | Metamorphic rock, contact metamorphism |
| Hyaloclastite | rock/mineral | grain size mm | Volcanic glass, subaqueous eruption |
| Hyperpycnal flow | process | kg/m³, m/s | Turbidity current, sediment-laden plume |
| Hypopycnal flow | process | kg/m³, m/s | Plume, buoyant discharge |
| Hypoxia | oceanography | mg/L O₂, % saturation | Dead zone, eutrophication, anoxia |
| Hoar frost | atmosphere | °C, RH | Deposition, frost, radiation cooling |
| Holocene Thermal Maximum | climate | °C anomaly | Paleo climate, Holocene optimum |
| Hot spring | hydrology | °C, flow L/s | Geothermal, geyser, hydrothermal |
| Hotspot | tectonics | mm/yr plate motion | Mantle plume, volcanic chain |
| Hummock | landform | m height | Knoll, hummocky moraine, permafrost |
| Humid climate | climate | mm/year precipitation | Tropical, temperate, monsoon |
| Humic acid | soil | mg/kg, % organic | Organic matter, humus, soil fertility |
| Hygroscopic growth | process | % water uptake, RH | Aerosols, hygroscopicity |
| Heterosphere | atmosphere | km altitude | Homosphere, thermosphere, exosphere |
| Homosphere | atmosphere | km altitude | Tropo-, stratosphere, mixing |
| Hydrometeor | atmosphere | mm size | Raindrop, snowflake, graupel |
| Hyperspectral imaging | method | nm spectral resolution | Remote sensing, spectral signature |
Descriptions
Hydrology
The science that studies Earth’s water—its distribution, movement, and properties—covering rivers, aquifers, and precipitation (USGS).
Hydrosphere
All the water on, under, and above Earth’s surface, including oceans, glaciers, groundwater, and vapor.
Hydrologic cycle
The continuous circulation of water between atmosphere, land, and oceans via evaporation, condensation, precipitation, and flow.
Hydrograph
A graph showing river discharge over time, used to analyze floods and watershed response.
Hydrogeology
Study of groundwater occurrence, movement, and quality within soil and rock (AGI).
Hydraulic conductivity
A measure of a material’s ability to transmit water, used to describe aquifer flow rates.
Headwaters
The upstream origin of a stream or river, often in hills or mountains.
Headland
A point of high land jutting into the sea formed by resistant rock protecting adjacent bays.
Headwall
The steep cliff at the back of a glacial cirque or landslide head; common in alpine terrain.
Headscarp
The exposed steep face at the top of a landslide where the ground has ruptured.
Heat
Thermal energy transferred by conduction, convection, or radiation influencing weather, climate, and geology.
Heat capacity
Amount of heat required to raise a substance’s temperature by one degree; important in climate and oceanography.
Heat flux
Rate of heat transfer per unit area, used for Earth’s surface and geothermal studies.
Heat flow
The movement of geothermal heat from Earth’s interior to the surface, measured in milliwatts per square meter.
Heat island
Urban areas that are warmer than surrounding rural zones due to surfaces and human activity (NOAA).
Heat index
A combined temperature and humidity measure that estimates how hot it feels to humans.
Heat sink
A system or reservoir that absorbs and stores heat energy, such as oceans or polar ice.
Heat wave
A prolonged period of unusually hot weather, often causing health and infrastructure impacts (NOAA).
Hail
Frozen precipitation in concentric layers that forms in strong thunderstorms and can damage crops and structures.
Haboob
A sudden, intense dust or sand storm driven by thunderstorm outflows common in arid regions.
Haze
Reduced visibility caused by fine particles or pollutants scattering sunlight in the atmosphere.
Halo
A ring of light around the Sun or Moon produced by refraction through ice crystals in high clouds.
Hurricane
A tropical cyclone with sustained winds ≥119 km/h; causes wind damage, heavy rain, and storm surge (NOAA).
Hadean
Earliest eon of Earth’s history (~4.6–4.0 Ga) when the planet was forming and cooling.
Halite
Common evaporite mineral (rock salt) formed by evaporation of seawater, used as an indicator of arid paleoenvironments.
Halocline
A sharp change in salinity with depth that affects water density and mixing in oceans and lakes.
Halogenated? (excluded)
n/a
Harmattan (wind)
A dry, dusty trade wind that blows from the Sahara over West Africa, reducing visibility and humidity.
Harmful algal bloom
Dense growths of algae that can produce toxins and cause oxygen depletion in water bodies.
Hartebeest? (excluded)
n/a
Harness? (excluded)
n/a
Harbor
A sheltered coastal area where ships can anchor; formed naturally or enhanced by human structures.
Hardness
A mineral property indicating resistance to scratching; commonly expressed on the Mohs scale for identification.
Harmonic tide
A component of tidal motion extracted in tidal harmonic analysis to predict sea levels.
Harsh? (excluded)
n/a
Hartz? (excluded)
n/a
Haze layer? covered by Haze entry
n/a
Headland cliff? covered by Headland
n/a
Hjulström curve
A diagram relating river flow velocity to sediment erosion, transport, and deposition (sedimentology).
High (atmospheric high)
A region of higher atmospheric pressure associated with sinking air and generally stable, dry conditions.
Hill
A raised landform smaller than a mountain, formed by tectonics, erosion, or deposition.
Hinge fault? (specialist)
A localized zone of bending in layered rocks; used in structural geology contexts.
Horsetail? (excluded)
n/a
Horn
A sharp, pyramid-shaped mountain peak carved by several glaciers eroding a mountain from different sides.
Horst
An uplifted block bounded by normal faults, commonly paired with a graben in extensional tectonic settings.
Horizon
A distinct soil layer with characteristic color, texture, and composition; used to describe soil profiles.
Humus
Dark, stable organic material in soil resulting from decomposed plant matter, important for fertility.
Humidity
Amount of water vapor in air; affects comfort, cloud formation, and precipitation processes.
Hygrometer
Instrument for measuring atmospheric humidity; common types include capacitive and sling psychrometers.
Hydrometer
Instrument that measures liquid density or specific gravity, used for salinity and brine concentration.
Hydrophone
Underwater microphone used to record and measure sounds in oceans and lakes (marine mammals, earthquakes, whales).
Hydrothermal vent
Seafloor discharge of hot, mineral-rich fluids from tectonic spreading centers; supports unique ecosystems.
Hydrothermal alteration
Chemical and mineralogical changes in rock due to interaction with hot fluids, often near intrusions or vents.
Hydrate
Ice-like compounds where water molecules trap gas (often methane) under high pressure and low temperature in sediments.
Hydrocarbon
Organic compounds of hydrogen and carbon that form petroleum and natural gas, major energy resources.
Hydrocarbon seep
Natural release of hydrocarbons from the seafloor supporting unique biological communities and forming gas hydrates.
Hydrostatic pressure
Pressure exerted by a fluid at equilibrium due to gravity; increases with depth in oceans and lakes.
Hydrography
Mapping and measurement of water bodies’ physical features, including depth, tides, and currents.
Hydroplaning? (transport) excluded
n/a
Hydrosphere coupling? covered by Hydrosphere
n/a
Hydraulic jump
A sudden transition from fast, supercritical to slow, subcritical flow releasing energy; seen in rivers and spillways.
Hydraulic conductivity
Measure of how easily water moves through pore spaces or fractures in soil and rock.
Hydraulic fracturing
Injection of fluid at high pressure to open rock fractures and enhance hydrocarbon extraction; linked to seismicity concerns.
Hydraulic gradient
Slope of hydraulic head driving groundwater flow; key parameter in Darcy’s law calculations.
Hydrological modeling
Computer simulation of water movement through landscapes for flood prediction, water resources, and planning.
Hydroclimate
The climate elements that control water availability like precipitation, evapotranspiration, and runoff.
Hydrologic unit
A mapped watershed area used for water-resource management and reporting (USGS hydrologic unit codes).
Hydrothermal plume
Buoyant mixture of hot fluid and entrained seawater rising from hydrothermal vents, transporting heat and minerals.
Hypsometry
Study and representation of land elevation distribution across an area, often summarized by a hypsometric curve.
Hypsometric curve
A graph showing the proportion of land area at different elevations, used to infer landscape development.
Hypsometric integral
A single metric from the hypsometric curve that indicates landscape maturity and tectonic activity.
Hjulström curve
Graph used to predict whether sediment will erode, transport, or deposit at a given flow velocity.
Hypocenter
The subsurface point where an earthquake rupture begins; epicenter is the surface projection.
Hypocenter depth
Depth of the earthquake hypocenter; shallow quakes (<70 km) often cause more surface damage.
Hypolimnion
The cold, dense bottom layer of a stratified lake that may become oxygen-poor in summer.
Holocene
The current geologic epoch starting ~11,700 years ago, encompassing the rise of human civilizations.
Holomictic lake
A lake that mixes completely from surface to bottom at least once a year, enabling full oxygen renewal.
Hominin? (excluded biological)
n/a
Hornfels
Dense, fine-grained metamorphic rock formed by heat from an intrusive body altering adjacent rocks.
Hyaloclastite
Glassy volcanic breccia formed when hot lava shatters on contact with water or ice during eruptions.
Hyperpycnal flow
A dense, sediment-rich river plume that sinks and flows along the seabed, transporting large sediment loads to deep water.
Hypopycnal flow
A buoyant freshwater plume that spreads across the surface when less dense than receiving water.
Hypoxia
Low dissolved oxygen conditions in water that can cause mass mortality of aquatic life (NOAA).
Hoar frost
Feathery ice crystals deposited on surfaces by direct vapor-to-ice deposition under clear, cold conditions.
Holocene Thermal Maximum
A mid-Holocene interval of relatively warmer climate in many regions; timing and magnitude vary regionally.
Hot spring
Surface discharge of geothermally heated groundwater; often associated with volcanic areas and geothermal systems.
Hotspot
A surface expression of a deep mantle thermal anomaly producing localized volcanic activity (e.g., island chains).
Hummock
Small, rounded mounds in landscapes often formed by glacial, peatland, or periglacial processes.
Humid climate
Climate regimes characterized by abundant moisture and regular precipitation supporting dense vegetation.
Humic acid
Complex organic compounds from decomposed plant material that influence soil structure and nutrient availability.
Hygroscopic growth
The uptake of water vapor by particles as relative humidity increases, affecting visibility and cloud formation.
Heterosphere
Upper atmospheric region where gas composition varies with altitude due to molecular diffusion.
Homosphere
Lower atmospheric layer where gases are well mixed and composition is roughly uniform.
Hydrometeor
Any water or ice particle in the atmosphere, including rain, snow, sleet, and cloud droplets.
Hyperspectral imaging
Remote sensing technique capturing many narrow spectral bands to distinguish minerals, vegetation, and materials.