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Tornadoes of 2022
The tornadoes of 2022 brought 1,331 preliminary US tornadoes, a record March count of 293, EF4 tornadoes at Winterset, Iowa, and Bryan County, Georgia, and 23 fatalities.
Tornadoes of 2023
The tornadoes of 2023 brought about 1,200 U.S. tornadoes and 86 deaths, defined by a record March, the Rolling Fork, Mississippi EF4, and the March 31 outbreak, one of the largest single-day outbreaks in U.S. history.
Tornadoes of 2024
The tornadoes of 2024 produced 1,796 confirmed tornadoes in the United States, the second-highest annual count on record behind 2004, with 54 deaths across 17 states.
Tornadoes of 2025
The tornadoes of 2025 in the United States produced 1,559 preliminary tornadoes, the fifth-highest total on record, including an EF5 near Enderlin, North Dakota, the first since 2013.
Tornadoes of 2026
The tornadoes of 2026 include a record 148 tornadoes in Illinois by June, a deadly March outbreak, and a destructive July EF3 near Appleton, Wisconsin.
Tornadoes striking downtown areas of large cities
Tornadoes striking downtown areas of large cities are tornadoes whose paths cross a major city's downtown core, such as Salt Lake City in 1999 and Atlanta in 2008.
Tornadogenesis
Tornadogenesis is the process by which a tornado forms, concentrating existing thunderstorm rotation into a small, intensely spinning column of air in contact with the ground.
Torridonian
The Torridonian is a thick succession of largely undeformed Proterozoic sedimentary rocks in northwest Scotland, deposited mainly by rivers between about 1,200 and 950 million years ago.
TORRO scale
The TORRO scale, or International Tornado Intensity Scale, is an 11-point scale rating tornado intensity by wind speed from T0 to T10, devised in 1972 by Terence Meaden.
Tortonian
The Tortonian is a geologic stage of the Miocene epoch, spanning roughly 11.63 to 7.246 million years ago and lying between the Serravallian and Messinian.
Total nitrogen
Total nitrogen (TN) is the sum of all forms of nitrogen in a water sample, including nitrate, nitrite, ammonia, and organic nitrogen, and a core indicator in lake monitoring.
Total phosphorus
Total phosphorus (TP) is a water-quality measurement of all phosphorus in a water sample regardless of chemical form, obtained by converting every phosphorus compound to orthophosphate before analysis.
Tourmaline
Tourmaline is a group of more than 40 borosilicate mineral species with prismatic crystals and one of the widest color ranges of any gemstone, from red to green and blue.
TR-55 (hydrology)
TR-55, Technical Release 55, is a USDA publication presenting simplified procedures for estimating storm runoff volume, peak discharge, and storage volumes in small United States watersheds.
Tracer experiment
A tracer experiment introduces a detectable dye, isotope, gas, or particle into water, air, or sediment and follows it to measure movement, mixing, and travel time.
Tracer test
A tracer test introduces a tracer such as a fluorescent dye, salt, or isotope into water and monitors its arrival downstream to characterize groundwater flow paths, velocities, and connectivity.
Trade winds
Trade winds, also called the tropical easterlies, are the persistent east-to-west winds on both sides of the equator, blowing from the subtropical high-pressure belts toward the equatorial low.
Tramontane
The tramontane, from the Latin for 'beyond the mountains', is a turbulent regional wind of southern France that blows through the Aude valley with gusts over 100 km/h.
Transform fault
A transform fault, or conservative plate boundary, is a strike-slip boundary where two plates slide horizontally past each other, proposed by J. Tuzo Wilson in 1965.
Transgressive systems tract
The transgressive systems tract is a subdivision of a depositional sequence in sequence stratigraphy, comprising deposits accumulated from the onset of coastal transgression until maximum transgression of the coast.
Transient climate response
The transient climate response (TCR) measures the warming at the time atmospheric carbon dioxide doubles, assessed by the IPCC at a best estimate of 1.8°C.
Transient electromagnetic method
The transient electromagnetic method (TEM), also called time-domain electromagnetic or TDEM surveying, maps subsurface conductivity from the decay of induced electromagnetic fields after transmitter turn-off.
Transient response to cumulative emissions
The transient response to cumulative emissions, or TCRE, is the ratio of global warming to total CO2 emitted, about 1.65°C per 1000 gigatonnes of carbon.
Transient storage
Transient storage is the temporary detainment of stream solutes in slow-moving zones like eddies and porous gravel, forming the basis of the transient storage model introduced by Bencala and Walters in 1983.
Transmissivity (hydrogeology)
Transmissivity is an aquifer property measuring the rate water is transmitted through a unit width under a unit hydraulic gradient; it equals hydraulic conductivity times aquifer thickness.
Transpiration
Transpiration: movement of water vapor from soil through plants out of leaf stomata; dominant terrestrial water flux, over 60% of evapotranspiration, driven by cohesion-tension, studied since Stephen Hales (1727).
Transpression
Transpression is a style of deformation in which strike-slip shearing combines with shortening across the shear zone, a term introduced by W. B. Harland in 1971.
Transtension
Transtension is rock deformation combining strike-slip shearing with extension across the shear zone, forming pull-apart basins; the term was introduced by W. Brian Harland in 1971.
Transverse Mercator projection
The Transverse Mercator projection, also called the Gauss-Krüger projection, is a conformal map projection whose scale is true along a central meridian, used in UTM and the British National Grid.
Travel-time tomography
Travel-time tomography is an imaging method that inverts seismic wave arrival times to reconstruct the Earth's internal velocity structure, adapted from medical imaging in the 1970s.