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Typhoon Megi (2010)
Typhoon Megi, known in the Philippines as Typhoon Juan, was a super typhoon of October 2010, the strongest tropical cyclone worldwide that year, striking the Philippines, Taiwan, and China.
Typhoon Mekkhala (2026)
Typhoon Mekkhala, known in the Philippines as Severe Tropical Storm Francisco, was a powerful June 2026 Pacific typhoon that passed the Philippines and Taiwan before hitting Japan with rain.
Typhoon Morakot (2009)
Typhoon Morakot was a tropical cyclone that struck Taiwan on 7–9 August 2009, dropping up to 2,635 mm of rain and triggering the deadly Shiaolin landslide.
Typhoon Muifa (2022)
Typhoon Muifa, known in the Philippines as Typhoon Inday, was a severe September 2022 Pacific typhoon that hit China, the first since 1949 to land in four provinces.
Typhoon Noul (2026)
Typhoon Noul, known in the Philippines as Tropical Storm Kiyapo and in China as Hongxia, was a severe typhoon that made landfall in Guangdong, China, near Hong Kong in July 2026.
Typhoon Ragasa
Typhoon Ragasa, known in the Philippines as Super Typhoon Nando, was a powerful 2025 western Pacific cyclone that killed dozens and made landfall in Guangdong, China.
Typhoon Rai
Typhoon Rai, known in the Philippines as Super Typhoon Odette, was a powerful typhoon that crossed the Philippines as a Category 5 storm in December 2021, killing more than 400 people.
Typhoon Rammasun (2014)
Typhoon Rammasun, known in the Philippines as Typhoon Glenda, was a powerful typhoon that struck the Philippines, southern China, and northern Vietnam in July 2014, killing well over 100 people.
Typhoon Saola (2023)
Typhoon Saola, known in Hong Kong as Super Typhoon Saola (苏拉), was an intense 2023 typhoon that forced Hong Kong's first Hurricane Signal No. 10 since 2018.
Typhoon Sinlaku (2026)
Typhoon Sinlaku (2026), also Super Typhoon Sinlaku, was a powerful western Pacific typhoon in April 2026 that struck Micronesia and the Northern Mariana Islands, killing at least twelve people.
Typhoon Thelma (1991)
Typhoon Thelma, known in the Philippines as Tropical Storm Uring, was a weak tropical storm whose flash floods killed thousands in Ormoc City, Leyte, in November 1991.
Typhoon Tip
Typhoon Tip, also called Super Typhoon Tip or Typhoon Warling, was the most intense tropical cyclone on record, hitting 870 mb in October 1979 before striking Japan.
Typhoon Yagi (ヤギ)
Typhoon Yagi, known in the Philippines as Typhoon Enteng, was a super typhoon that struck the Philippines, China, and Vietnam in September 2024, killing over 700 people.
Typhoon Yutu (2018)
Typhoon Yutu, known in the Philippines as Typhoon Rosita, was a Category 5-equivalent typhoon that struck Tinian and Saipan in October 2018, the strongest to hit the Marianas on record.
Tyrone mine
The Tyrone mine is an open-pit copper mining complex in Grant County, New Mexico, about 10 miles south of Silver City, owned by Freeport-McMoRan and operating since 1967.
U.S. state and territory temperature extremes
The U.S. state and territory temperature extremes are NOAA-certified record highs and lows for all 50 states, D.C., and inhabited territories, including the 134°F Death Valley world record.
UAV photogrammetry
UAV photogrammetry is a remote sensing method that reconstructs 3D terrain models, point clouds, and orthophotos from overlapping drone images, using structure from motion algorithms.
Udina
Udina (Bolshaya and Malaya Udina) is a pair of Holocene stratovolcanoes at the south end of Kamchatka's Kliuchevskaya group, Russia, with no known Holocene eruptions but seismic unrest in 2017-2019 suggesting possible magmatic reawakening.
Udokan Plateau
Udokan Plateau (Udokan volcanic plateau): a 3,000 km2 Miocene-to-Holocene volcanic field on the NE Baikal Rift in Siberia, Russia, with cinder cones, domes, and maars; last eruption at Chepe, 220 BCE.
Uinta Basin
The Uinta Basin is a structural basin in northeastern Utah and northwestern Colorado that holds Utah's principal oil and gas resources, producing 93 percent of the state's crude.
UK Climate Projections
The UK Climate Projections (UKCP18) are the Met Office's national climate projections, observations, and tools covering how the UK's climate is likely to change through 2100, replacing UKCP09.
Ulexite
Ulexite, nicknamed TV rock, is a soft white fibrous sodium calcium borate mineral found in arid evaporite deposits, known for transmitting images along its fibers.
Ultisols
Ultisols are one of the twelve orders of USDA Soil Taxonomy, strongly weathered acidic forest soils of humid temperate and tropical regions with base saturation below 35 percent.
Ultra-short baseline positioning
Ultra-short baseline (USBL) positioning is an underwater acoustic technique that determines the 3D position of submerged targets, such as ROVs, from a single compact transducer array on a surface vessel.
UNAVCO
UNAVCO was a Boulder, Colorado non-profit consortium, founded in 1984 to share GPS equipment and archive geodetic data for Earth science research, merging with IRIS in 2023.
Unconfined aquifer
An unconfined aquifer, or water-table aquifer, is a groundwater layer whose upper boundary is the water table, which recharges directly from the surface and is vulnerable to drought and contamination.
Unconformity
An unconformity is a surface of erosion or non-sedimentation between rock bodies that represents a gap in the stratigraphic record, spanning thousands or millions of years.
Undertow (water waves)
Undertow, also called bed return flow, is the wave-driven seaward return flow near the seabed in the surf zone, compensating for the onshore transport by breaking waves.
Unexplained volcanic eruption
An unexplained volcanic eruption, often called a mystery eruption, is a large eruption identified from polar ice cores rather than written history, such as the still-unlocated 1809 event.
Unified Model
The Unified Model is the Met Office's Fortran-based model simulating atmosphere, ocean, and land for weather forecasting and climate projection, with one codebase running from urban-scale forecasts to century-long climate simulations.