1933 Atlantic hurricane season One of the busiest Atlantic hurricane seasons on record, the 1933 season produced more than twenty tropical storms and underscored limits of pre-satellite detection and historical…
1944 Great Atlantic Hurricane A powerful September 1944 tropical cyclone that moved along the U.S. Atlantic coast from North Carolina to New England, killing several hundred people and causing widespread damage…
1963 Atlantic hurricane season Summary of the 1963 Atlantic hurricane season, its timeline, notable storms—especially Hurricane Flora—and the human and regional impacts across the Caribbean and Atlantic basin.
1976 Pacific hurricane season Summary of the 1976 Pacific hurricane season, its notable storms (Kathleen, Liza, Madeline), impacts, meteorological context, and lasting significance.
1977 Atlantic hurricane season An unusually quiet Atlantic hurricane season in 1977 produced only six named storms and began late, with the first system forming on August 29. Hurricane Anita was the season’s mos…
1979 Pacific typhoon season Summary of the 1979 Pacific typhoon season: activity summary, agencies and naming, notable storms (including record‑setting Typhoon Tip), impacts, and meteorological significance.
1983 Atlantic hurricane season An unusually quiet Atlantic hurricane season with only four named storms, notable for Hurricane Alicia's damage in Texas and one of the lowest ACE totals on record during the satel…
1984 Atlantic Hurricane Season: overview, storms, and impacts 1984 Atlantic hurricane season Summary of the 1984 Atlantic hurricane season, its timeline, storm statistics, notable systems such as Hurricane Diana and Hurricane Lili, and the season's impacts and distinctions…
1985 Atlantic hurricane season Summary of the 1985 Atlantic hurricane season: dates, notable storms (Elena, Gloria, Juan, Kate), unusual late activity, general impacts and historical context.
1994 Atlantic hurricane season A below-average Atlantic hurricane season (June 1–Nov 30, 1994) that produced seven named storms, three hurricanes and no major hurricanes; notable for long‑lived Hurricane Gordon…
1995 Atlantic hurricane season: an unusually active year 1995 Atlantic hurricane season Overview of the 1995 Atlantic hurricane season, its meteorological causes, major storms and impacts, records set, and the season's significance for forecasting and preparedness.
1995 Eastern and Central Pacific Hurricane Season — Summary and Notable Storms 1995 Pacific hurricane season Overview of the 1995 eastern and central Pacific hurricane season: 11 cyclones, 10 tropical storms, 7 hurricanes and 3 major hurricanes, with notable impacts from Hurricane Ismael…
1996 Pacific hurricane season Overview of the 1996 Pacific hurricane season: timing, activity, notable storms (including Hurricane Douglas), impacts on Mexico, meteorological context, and monitoring agencies.
2004 Atlantic hurricane season An above‑average Atlantic hurricane season running June 1–November 30, 2004, notable for 15 named storms, exceptionally high energy, and several destructive hurricanes that struck…
2005 Pacific hurricane season Summary of the 2005 northeast Pacific hurricane season, covering activity, notable storms, impacts, forecasts, and how it compared to other seasons.
2006 Atlantic hurricane season Summary of the 2006 Atlantic hurricane season: dates, storm and hurricane counts, meteorological influences (El Niño, Saharan Air Layer), notable records such as Zeta's calendar-ye…
2008 Atlantic hurricane season The 2008 Atlantic hurricane season produced 16 named storms, 8 hurricanes (5 major). It ran June 1–November 30; Arthur formed May 30. Gustav and Ike were among the most destructive…
2008 Pacific hurricane season A near‑average Pacific hurricane season that ran May 15–November 30, 2008, producing 17 named storms and seven hurricanes across the Eastern and Central Pacific basins.
2013 Atlantic hurricane season A below‑average Atlantic hurricane season running from June 1 to November 30, 2013, notable for early Tropical Storm Andrea and for producing no major hurricanes for the first time…
2016 Atlantic hurricane season Above-average Atlantic hurricane season in 2016: 15 named storms, 7 hurricanes, 4 major hurricanes; notable for Hurricane Matthew and elevated ACE driven by favorable ocean and atm…
2018 Atlantic hurricane season Summary of the 2018 Atlantic hurricane season: storms, notable hurricanes, records, impacts, meteorological context, and post‑season assessment.
2019 North Indian Ocean cyclone season Overview of the 2019 North Indian Ocean cyclone season, its notable storms, meteorological context, impacts and records, with emphasis on storms such as Pabuk, Fani, Vayu, Kyarr an…
2019 Pacific typhoon season — overview, major storms and impacts 2019 Pacific typhoon season Summary of the 2019 Pacific typhoon season, its meteorology, major storms (Hagibis, Lekima, Faxai, Kammuri, Phanfone), impacts, naming practices and aftermath.
Abenakiite-(Ce) Abenakiite-(Ce) is a rare cerium-dominant mineral first identified in a Canadian quarry. Pale brown and crystalline, it is mildly radioactive, softer than fluorite, and primarily o…
Abernathyite: pale yellow uranium-arsenate mineral Abernathyite Abernathyite is a pale yellow, highly radioactive uranium-arsenate mineral first found in Emery County, Utah. It forms fragile crystalline coatings and is principally of scientific…
Above Mean Sea Level (AMSL): definition, measurement, and uses Above mean sea level Above mean sea level (AMSL) denotes a vertical position relative to the averaged sea surface; used in surveying, aviation, mapping, engineering and atmospheric science as a common…
Abswurmbachite Abswurmbachite is a rare metallic mineral, typically black to dark brown, named for German mineralogist Irmgard Abs‑Wurmbach and reported from localities on Andros Island, Greece.
Accumulated Cyclone Energy (ACE): definition, calculation, and uses Accumulated cyclone energy Accumulated Cyclone Energy (ACE) quantifies tropical cyclone activity by summing squared six-hourly wind speeds over a storm's life. It is widely used to compare seasons and study…
Achondrite — Stony Differentiated Meteorites Achondrite Achondrites are stony meteorites that lack chondrules and record melting and differentiation on their parent bodies. They include basaltic, plutonic, lunar, Martian, and primitive…
Actinolite — a green amphibole mineral of metamorphic rocks Actinolite Actinolite is an amphibole mineral commonly green to black, found in metamorphic rocks. It ranges from crystalline specimens to fibrous forms, and is related to tremolite and nephr…
Active fault An active fault is a fracture in the Earth's crust that has moved recently and is likely to produce future earthquakes; studied to assess seismic hazard and guide planning.
Acuminite: a colorless, sharply pointed mineral from Ivigtut Acuminite Acuminite is a colorless mineral known for sharply pointed crystal terminations. It is chiefly recorded from the Ivigtut cryolite deposit in Greenland and is soft enough to be scra…
Adamite — zinc arsenate mineral Adamite Adamite is a zinc arsenate hydroxide mineral (Zn2(AsO4)(OH)) known for yellow to green crystalline colors, brittle tenacity, occurrence in oxidized arsenic-rich deposits, and popul…
Aeolian processes: wind-driven erosion, transport and deposition Aeolian processes Aeolian processes are wind-driven actions that erode, transport, and deposit sediment on Earth and other planets. They create dunes, dust storms and loess and affect ecosystems, cl…
African Plate: structure, motion, and geological significance African plate Comprehensive overview of the African Plate: extent, internal subdivisions, boundaries, rifting (East African Rift, Red Sea), motion, geological history from Gondwana, hazards, and…
Aftershock (seismic event) Aftershock An aftershock is a smaller earthquake that follows a larger mainshock in the same region. This article explains causes, typical patterns, hazards, monitoring and how aftershocks di…
Agate: banded chalcedony variety of quartz, formation, types, and uses Agate Agate is a banded form of microcrystalline quartz used as gemstone and ornamental stone; formed by rhythmic silica deposition in cavities, with many varieties, historical uses, and…
Age of the Earth: how scientists determine Earth's age Age of the Earth Modern estimates place Earth's age at about 4.54 billion years. This article explains the evidence, radiometric methods, oldest materials, history of the problem, uncertainties, an…
Agronomy: the science of soil, crops, and sustainable production Agronomy Agronomy studies soil–plant systems to improve the production and quality of food and fiber. It combines soil science, crop physiology, pest management and technology for sustainab…
Air: Composition, Properties, Life Role, Uses, Pollution, and History Air Air is the gaseous envelope around Earth that supports life, shapes weather, enables technologies, and is subject to pollution and climate change. Overview of composition, properti…
Air mass (meteorology) Air mass A large body of air with fairly uniform temperature and humidity that forms over a source region and influences weather as it moves and interacts with other air masses.
Aliso Creek (Orange County, California) Aliso Creek A coastal stream draining the Santa Ana Mountains to the Pacific. About 19 miles long with a 30.4 sq mi watershed, known for urbanization, several tributaries, pollution challenges…
Allan Hills 84001 (ALH84001) — Martian meteorite Allan Hills 84001 ALH84001 is a martian orthopyroxenite meteorite found in Antarctica in 1984. Famous for a controversial 1996 claim of possible microfossils, it remains important for studies of ear…
Alluvial fan Fan-shaped sediment deposit formed where high-energy streams spread onto flatter ground; common at mountain fronts and important for groundwater, agriculture, debris flows and floo…
Alpine climate High‑mountain climate found above the tree line and below permanent snow, characterized by cool summers (no month above 10°C), cold winters, strong radiation, and specialized alpin…
Alpine Fault — major plate boundary fault in New Zealand Alpine fault The Alpine Fault is the principal active geological fault on New Zealand's South Island, marking the Pacific–Indo-Australian plate boundary and responsible for uplift of the Southe…
Alpine (Alpide) orogeny — origin and development of the Alpide belt Alpine orogeny Mountain-building event from the late Mesozoic to present that produced the Alpide belt across southern Europe and western to central Asia through collisions of Africa, India and m…
Anahim Volcanic Belt An east–west chain of volcanoes across central British Columbia formed by the Anahim hotspot; includes shield volcanoes and cones such as Rainbow, Ilgachuz, Itcha and Nazko.
