Nature

Geysir: Iceland's iconic geothermal fountain Geysir Geysir is a historic hot spring in Iceland's Haukadalur valley that gave its name to all geysers. Its eruptions are irregular; nearby Strokkur is more active and a major tourist dr…

Gigantism A rare endocrine disorder in which excessive growth hormone before the end of childhood causes abnormal height and tissue enlargement; distinct from acromegaly.

Glaucous: bluish‑green/grey colour and botanical term Glaucous Glaucous denotes a bluish‑green or bluish‑grey hue and, in botany, a pale waxy bloom on plant surfaces. The term appears in species names and describes protective coatings, plumage…

Gleba: the spore-bearing inner tissue of some fungi Gleba Gleba is the internal, often fleshy spore-bearing tissue found in certain fungi (puffballs, stinkhorns, truffles). It varies in texture and dispersal strategy and plays a central r…

Gonad: the primary reproductive organ (ovary and testis) Gonad Gonads are the primary reproductive organs — ovaries in females and testes in males — that produce gametes and sex hormones. They play central roles in reproduction, sexual develop…

Goniatite — Paleozoic ammonoid cephalopods (Order Goniatitida) Goniatite Goniatites are extinct ammonoid cephalopods that lived from the Middle Devonian to the end of the Permian. Known for their chambered external shells and simple goniatitic sutures,…

Granule (small particle) Granule A granule is a small, discrete particle or grain used as a general descriptive term across science and industry, from biology and pharmacy to geology, materials and computing.

Grassland: characteristics, distribution, types and ecological importance Grassland Grasslands are ecosystems dominated by grasses with few trees; they include prairies, steppes and savannas, occur on most continents, support grazing and biodiversity, and provide…

Grove (nature) A grove is a small grouping of trees with little undergrowth, occurring naturally or planted as orchards. This article outlines characteristics, types, cultural roles, ecological i…

Gryphaea — extinct ‘devil's toenail’ oysters of the Mesozoic and Paleogene Gryphaea Gryphaea is an extinct genus of oysters known as 'devil's toenails'. Common Mesozoic to Oligocene fossils, they are recognizable by a large curved valve and a smaller lid and are f…

Guano: nutrient-rich excrement used as fertilizer and its history Guano Guano is the accumulated droppings of bats and birds, rich in nitrogen, phosphate and potassium. This entry explains composition, formation, historical trade, uses in agriculture,…

Halomonadaceae: salt‑tolerant bacteria of marine and saline environments Halomonadaceae Halomonadaceae is a family of mostly halophilic, Gram‑negative bacteria in the Gammaproteobacteria. They occur in saline habitats and have ecological, biotechnological, and bioreme…

Handicap principle: costly signals in animal communication and its implications Handicap principle The handicap principle explains how costly traits can serve as honest signals in sexual selection and communication. Covers origin, mechanism, evidence, criticisms, and broader app…

Harpoon: spear-like implement for fishing, whaling, and hunting Harpoon A harpoon is a barbed, spear-like tool used to catch large fish and marine mammals. This article describes its design, historical development, types, uses, and legal and ethical is…

Helmholtz resonance Helmholtz resonance is the characteristic low-frequency vibration of air in a cavity with an opening, important in acoustics, instruments, and noise control.

Hemerophile: species that benefit from human-altered environments Hemerophile Hemerophiles are plants and animals that thrive in habitats changed by humans. This article explains their traits, examples, ecological role, and how they differ from related conce…

Heterochromia: Causes, Types, and Clinical Significance Heterochromia Heterochromia is a difference in iris coloration between or within the eyes. This article explains types, causes (genetic and acquired), diagnostic considerations, occurrences in a…

Hino River (Tottori Prefecture, Japan) Hino River The Hino River flows across western Tottori Prefecture from Mikuniyama to Miho Bay near Yonago. It supplies water to local communities, supports agriculture and ecosystems, and has…

Honeycomb Honeycomb is the wax structure built by honeybees of hexagonal cells used to store honey, pollen and to rear brood. It is notable for its geometry, material properties, and many hu…

Honeydew: sugary insect secretion from sap-feeding insects Honeydew Honeydew is the sticky, sugary excretion produced by sap-feeding insects. It influences plant health, fosters mutualisms (with ants and bees), and can be transformed into dark hone…

Hook echo: radar signature of rotating thunderstorms and tornado risk Hook echo Hook echo — a curved radar reflectivity pattern from precipitation and debris wrapped into a storm's rotating updraft; often indicates elevated tornado risk but is assessed with Do…

Horn: biological structures, instruments and cultural uses Horn Horn refers to projection structures on animals, horn-derived materials, musical instruments and signaling devices; this article covers types, formation, uses, and modern distincti…

Huandoy — glaciated peak of Peru's Cordillera Blanca Huandoy Huandoy is a 6,395 m glaciated mountain in Peru's Cordillera Blanca, noted for multiple summits, technical climbs, and its setting within Huascarán National Park near Huaraz and th…

Humidity: water vapor in the air and its effects Humidity Humidity describes the amount of water vapor present in the air. This article explains definitions, measurement methods, impacts on health and weather, and practical distinctions l…

Hunting: practices, history, regulation, and conservation Hunting Overview of hunting as a human activity and ecological process, its methods, cultural history, uses, regulation, and controversies including conservation and animal welfare concern…

Hurricane Alex (2010): June Atlantic Hurricane and Mexico Landfall Hurricane Alex (2010) Overview and impacts of Hurricane Alex (2010), a rare June Atlantic hurricane that formed early in the season and made landfall in northeast Mexico, causing fatalities, flooding an…

Hurricane Alma (1966) June 1966 Atlantic hurricane that struck western Cuba and the U.S. Southeast, producing peak winds near 125 mph, causing nearly 100 deaths and about $210 million in damage; the nam…

Hurricane Anita (1977) — Category 5 Atlantic hurricane Hurricane Anita Hurricane Anita was the only major hurricane of the quiet 1977 Atlantic season. It reached Category 5 strength and made landfall in northeastern Mexico, with at least 11 reported d…

Hurricane Beta (2005) Hurricane Beta A late‑October 2005 Atlantic hurricane that formed in the southwestern Caribbean, reached major hurricane strength, and made landfall on Nicaragua as a Category 2 storm.

Hurricane Bob (August 1991) — New England storm and impacts Hurricane Bob August 1991 Atlantic hurricane that struck the Mid-Atlantic and New England, causing widespread wind, flood and coastal damage; responsible for over $1 billion in state losses and…

Hurricane Bonnie (1998): overview, path, and impacts Hurricane Bonnie (1998) Hurricane Bonnie was a late‑August 1998 Atlantic storm that peaked as a major hurricane and made landfall near Wilmington and Cape Fear, North Carolina, causing deaths and about $1…

Hurricane Boris (1996) A brief account of Hurricane Boris, an early-season eastern Pacific storm in 1996 that rapidly strengthened before making landfall in southern Mexico, producing heavy rains and dea…

Hurricane Camille: 1969 Category 5 Atlantic hurricane and its impact Hurricane Camille Detailed overview of Hurricane Camille (1969): formation, rapid intensification, extreme intensity at Gulf landfall, coastal destruction in Mississippi, inland flooding in Virginia…

Hurricane Carla (1961): Major Texas landfall and legacy Hurricane Carla Hurricane Carla was a powerful 1961 Atlantic hurricane that struck the Texas coast as a Category 4, triggering a massive evacuation, widespread damage and a relatively low death to…

Hurricane Carmen (1974) Hurricane Carmen Hurricane Carmen was the most intense storm of the 1974 Atlantic season, reaching Category 4 and moving across the Yucatán Peninsula before striking the U.S. Gulf Coast in Louisian…

Hurricane Carol (1954) Hurricane Carol Hurricane Carol was a powerful late‑August 1954 hurricane that struck New England, causing widespread coastal flooding, wind damage, and becoming one of the costliest U.S. storms u…

Hurricane Dean (2007) — Category 5 Atlantic hurricane Hurricane Dean A powerful Category 5 Atlantic hurricane in August 2007 that crossed the Caribbean and made landfalls on Mexico's Yucatán Peninsula and Veracruz, causing wide agricultural damage a…

Hurricane Diana (1990) Hurricane Diana A Category 2 Atlantic hurricane in August 1990 that made landfall in Mexico, causing widespread flooding, over 130 fatalities and more than $100 million (1990 USD) in damage. The n…

Hurricane Dora (1964) — Northeast Florida landfall and legacy Hurricane Dora Hurricane Dora (1964) was a powerful Cape Verde hurricane that made landfall on Florida’s northeast coast, produced near-125 mph winds around Jacksonville, caused heavy damage, and…

Hurricane Dorian (2019): Category 5 storm that devastated parts of the Bahamas Hurricane Dorian Powerful 2019 Atlantic hurricane that reached Category 5 strength, stalled over the northwestern Bahamas causing catastrophic wind and flood damage, and later affected parts of the…

Hurricane Felix (2007) Hurricane Felix Powerful Category 5 Atlantic hurricane in early September 2007 that reached peak winds of about 175 mph and struck Central America, causing severe destruction and prompting large-s…

Hurricane Flora (1963): Deadly Category 4 storm that struck Haiti and Cuba Hurricane Flora Hurricane Flora was a slow-moving, destructive Atlantic hurricane in autumn 1963 that produced catastrophic flooding in Haiti and Cuba, causing an estimated 7,000–8,000 deaths and…

Hurricane Fran (1996) Hurricane Fran Powerful Category 3 Atlantic hurricane in 1996 that struck North Carolina, caused billions in damage and multiple deaths; the name Fran was retired after the season.

Hurricane Gilbert (1988): Overview, impacts, and legacy Hurricane Gilbert Hurricane Gilbert was a powerful 1988 Atlantic hurricane that produced catastrophic damage across the Caribbean, Mexico and parts of Texas and set record low pressure for its time.

Hurricane Hanna (2008) — overview, track, impacts and aftermath Hurricane Hanna An encyclopedia overview of Hurricane Hanna (2008): its development, meteorological characteristics, impacts across the Caribbean, the Bahamas and the United States, and its post-s…

Hurricane Harvey (2017): Category 4 landfalls, record rainfall, and recovery Hurricane Harvey Hurricane Harvey was a 2017 Category 4 Atlantic hurricane that stalled over Texas, producing unprecedented rainfall and catastrophic flooding around Houston and the Gulf Coast, cau…

Hurricane Hugo (September 1989) Hurricane Hugo Hurricane Hugo was a powerful Atlantic hurricane in September 1989 that devastated parts of the Caribbean and the U.S. Southeast, causing dozens of deaths, widespread homelessness,…

Hurricane Hunters: Aircraft Reconnaissance of Tropical Cyclones Hurricane Hunters Hurricane Hunters are specially equipped aircraft that fly into tropical cyclones to collect direct observations used for forecasting and research, primarily in the Atlantic and ea…