Earth science

Hurricane Hortense (1996): track, impacts, and legacy Hurricane Hortense A summary of Hurricane Hortense, a September 1996 storm that struck parts of the Caribbean and Atlantic Canada, its impacts, aftermath, and the retirement of the name.

Hurricane Humberto (2007) A fast-forming Category 1 hurricane that developed in the northwestern Gulf of Mexico on September 12–13, 2007, striking near High Island, Texas, and causing localized damage estim…

Hurricane Ingrid (2013) Hurricane Ingrid Category 1 Atlantic hurricane in September 2013 that impacted eastern Mexico simultaneously with a Pacific storm; caused multiple deaths and had its name retired and replaced by Im…

Hurricane Ioke (2006) — long-lived Central Pacific hurricane and typhoon Hurricane Ioke Hurricane Ioke was an unusually long-lived and powerful 2006 tropical cyclone that formed in the Central Pacific, reached Category 5 strength multiple times, and struck Wake Island…

Hurricane Isaac (2012): Caribbean and Gulf Coast Impacts Hurricane Isaac (2012) Hurricane Isaac (2012) was a slow-moving Category 1 Atlantic hurricane that struck the Caribbean and made landfall in southeast Louisiana on Aug 28, producing heavy rain, flooding,…

Hurricane Isidore (2002): overview, path, impacts, and retirement Hurricane Isidore Hurricane Isidore was the strongest storm of the 2002 Atlantic season. It affected the Caribbean, Mexico's Yucatán Peninsula and parts of the U.S., caused fatalities and major dama…

Hurricane Jeanne (2004) Hurricane Jeanne Powerful Atlantic hurricane of 2004 that produced catastrophic flooding in Haiti, made landfall in Florida near the same area hit by Frances, and caused roughly $7 billion in damag…

Hurricane Juan (2003) — Category 2 storm that struck Nova Scotia Hurricane Juan Hurricane Juan was a Category 2 hurricane that made landfall near Halifax, Nova Scotia, on September 29, 2003. It caused widespread wind and flood damage in Atlantic Canada, eight…

Hurricane Juan (1985) A brief encyclopedia entry on Hurricane Juan (1985): a relatively weak Atlantic hurricane that nevertheless caused about 24 deaths and roughly $1.5 billion in damage; its name was…

Hurricane Julia (2010): an unusually eastern Category 4 Atlantic hurricane Hurricane Julia (2010) Hurricane Julia (2010) was a rapidly intensifying Category 4 Atlantic hurricane notable for reaching major hurricane strength unusually far east in the basin and later weakening un…

Hurricane Lane (2006) — Category 3 Pacific hurricane that struck Sinaloa, Mexico Hurricane Lane (2006) Hurricane Lane (2006) was a major Category 3 Pacific hurricane that made landfall in Sinaloa, Mexico in September 2006, causing fatalities, extensive crop damage and about $203 mil…

Hurricane Linda (1997): powerful Eastern Pacific Category 5 storm Hurricane Linda (1997) Hurricane Linda was an exceptionally intense eastern North Pacific hurricane in 1997. It reached Category 5 intensity over open water and remained well offshore, producing little d…

Hurricane Ophelia (October 2017): storm overview and impacts Hurricane Ophelia Hurricane Ophelia was an October 2017 Atlantic hurricane that reached Category 3, followed an unusually eastward track, and caused fatalities, damage and widespread disruption acro…

Hurricane Ophelia (2005) A long‑lived and slow‑moving Atlantic hurricane of September 2005 noted for its erratic track off the U.S. East Coast and damage to eastern North Carolina and parts of New England…

Hurricane Stan (2005): a deadly Category 1 storm in Central America and Mexico Hurricane Stan Hurricane Stan was a Category 1 Atlantic hurricane in October 2005 that produced extreme rainfall, widespread flooding and landslides across Central America and Mexico, causing sev…

Hurricane Vince: a rare northeast Atlantic tropical cyclone Hurricane Vince Hurricane Vince was an unusual tropical cyclone of the 2005 Atlantic season that formed in cool northeastern Atlantic waters and made landfall on the Iberian Peninsula, challenging…

Hydrology: the science of water movement, distribution and quality Hydrology Hydrology studies the movement, distribution, and quality of water on Earth, including the water cycle, surface and groundwater, measurement methods, uses in water management, and…

Hydrosphere: Earth's Water Envelope and Its Role Hydrosphere The hydrosphere is the global system of all water on, above and below a planet's surface, including oceans, ice, groundwater and vapor, and its importance for climate, ecosystems a…

Hydrothermal vent: deep-sea hot springs and their ecosystems Hydrothermal vent Seafloor openings where heated, mineral-rich water escapes; hosts unique chemosynthetic life, forms black/white smokers, influences ocean chemistry, and informs origin-of-life rese…

Hygrometer — Instrument for measuring atmospheric humidity Hygrometer Overview of hygrometers: principles, common types (psychrometer, hair, capacitive, chilled mirror), history, applications in meteorology, HVAC, museums and calibration consideratio…

Hypocenter: the underground origin of earthquakes and ground zero of blasts Hypocenter Hypocenter denotes the subsurface point where an earthquake rupture begins or the ground point beneath a nuclear detonation; distinct from the surface epicenter and important in se…

Iapetus Ocean An ancient ocean that existed between roughly 600 and 400 million years ago, separating the paleocontinents that later collided to form Euramerica/Laurussia and leaving a suture pr…

Ice age: causes, history, and global impacts Ice age Long intervals of extensive continental and polar ice cover marked by cooler global climate, sea-level changes, and widespread geological and ecological effects.

Ice cap: definition, characteristics, formation, and importance Ice cap An ice cap is a dome-like mass of glacial ice covering less than 50,000 km². This article explains its form, behaviour, examples, role in climate and how it differs from ice sheets…

Ice core Long cylindrical samples of glacier ice that preserve layered records of past atmosphere and climate; recovered by deep drilling in polar and high‑altitude locations.

Ice pellets (sleet): formation, characteristics and distinctions Ice pellets Ice pellets are small, hard frozen precipitation formed when liquid droplets freeze before reaching the ground. This article explains formation, terminology (sleet, graupel, hail),…

Ice sheet (continental glacier) Ice sheet A vast, continuous mass of glacial ice covering more than 50,000 km². Ice sheets shape climate, store freshwater, and today persist mainly in Antarctica and Greenland.

Ice shelf A large, thick plate of ice formed where a glacier or ice sheet reaches the sea and floats or rests on the coastline; key to ice‑sheet stability, ocean interactions, and sea‑level…

Ice storm An ice storm is a winter weather event in which freezing rain coats surfaces with glaze ice, creating hazardous travel conditions, tree and power damage, and widespread disruptions…

Iceberg: formation, structure, types, hazards and ecological role Iceberg Large floating masses of freshwater ice that calve from glaciers or ice shelves; most of their volume lies underwater, they shape polar ecosystems and pose navigation hazards.

Igneous rock: formation, types, and uses Igneous rock Igneous rock forms by cooling of molten material (magma or lava). This article explains its formation, textures, classification, common examples, uses, and how it differs from sedi…

Imbabura Volcano Imbabura is an inactive Andean stratovolcano in northern Ecuador. It is snow-capped, has not erupted in over 14,000 years, and supports fertile agricultural foothills with maize, s…

Impact crater A bowl- to basin-shaped depression formed when a meteoroid, asteroid or comet strikes a solid planetary surface; studied for planetary history, hazards, and resources.

Indo-Australian Plate A major tectonic plate that carries Australia and part of the Indian region, and whose northern edge drives major mountain building and earthquakes.

Inflow (meteorology): moisture and heat transport into weather systems Inflow (meteorology) Inflow in meteorology is the movement of warm, moist air into storms and cyclones. It sustains convection, influences intensity and tornado potential, and is distinct from outflow…

Inland sea (epeiric or epicontinental sea) Inland sea An inland sea is a shallow body of marine water that covers part of a continental interior. This article explains formation, characteristics, notable examples and how they differ f…

Insolation — incoming solar radiation reaching Earth's surface Insolation Insolation is the solar radiation that reaches the top of the atmosphere and the Earth's surface. This article explains its meaning, measurement, controlling factors, history, and…

Intrusion (Geology): Subsurface Igneous Emplacements Intrusion Intrusion: melted rock (magma) that solidifies beneath Earth’s surface. Covers how intrusions form, common types (batholiths, sills, dykes), geological effects, examples and econom…

Iron ore: geology, types, mining and uses Iron ore Comprehensive overview of iron ore: principal minerals and deposits, how they form, mining and processing routes, role in steelmaking, global distribution, and environmental issues…

Jack Hills (Western Australia) — source of Earth's oldest known terrestrial zircons Jack Hills Range in Western Australia whose metamorphosed sedimentary rocks contain detrital zircons up to about 4.4 billion years old, used to study Hadean Earth conditions and early crustal…

Jade: minerals, properties, history and cultural significance Jade Jade is a term for two distinct minerals—nephrite and jadeite—valued for toughness and beauty. This article explains their composition, physical traits, history, cultural uses, and…

James Hansen — Climate Scientist, NASA Researcher, and Public Advocate James Hansen James E. Hansen (born 1941) is an American climatologist who led NASA's Goddard Institute for Space Studies, testified on global warming, advocated a 350 ppm CO2 goal, and remains…

Jet (lignite) — fossilized wood gemstone and mineraloid Jet (lignite) Jet is a compact, black variety of fossilized wood (lignite) prized as a gemstone and carving material; known for its deep black color, historical use in jewelry, and organic origi…

Jet stream High-altitude, narrow bands of fast-moving air that encircle the globe and strongly influence weather, aviation, and climate patterns.

Jingū Seamount — extinct guyot of the Hawaiian–Emperor chain Jingū Seamount Jingū Seamount is an extinct, flat-topped volcanic seamount in the Hawaiian–Emperor chain. Formed by hotspot volcanism and named for Empress Jingū, it records Pacific plate motion…

Joint (geology): Tensile fractures and their role in rocks Joint (geology) A joint is a tensile fracture in rock without shear offset. This article explains how joints form, their patterns and properties, effects on weathering and groundwater, and distinc…

Joint Typhoon Warning Center U.S. Navy–Air Force joint task force that provides tropical cyclone warnings, forecasts and analysis for U.S. government interests across the Pacific and Indian Oceans from Pearl H…

Jurassic (geological period) Jurassic Middle period of the Mesozoic Era (about 201 to 145 million years ago), noted for dinosaur dominance, breakup of Pangaea, rich marine life and important fossil formations.