5,021 articles
Three Forks Formation
The Three Forks Formation is a Late Devonian rock unit in the Williston Basin of North Dakota and Montana, and one of the two main reservoirs of the Bakken petroleum system.
Threshold slope
A threshold slope is a hillslope steepened to the limiting angle of stability, where further uplift or river incision is absorbed by landsliding rather than steepening.
Throughfall
Throughfall is the portion of precipitation that reaches the ground beneath a vegetation canopy, passing through gaps or dripping and splashing from leaves, branches, and stems.
Throughflow
Throughflow, also called interflow or subsurface stormflow, is the lateral movement of water through soil above a less permeable layer during storms, dominating steep catchments and contributing to streamflow.
Thrust fault
A thrust fault is a reverse fault with a low dip of 45 degrees or less, where the hanging wall is pushed up and over the footwall under horizontal compression.
Thunder
Thunder, also called a clap of thunder, is the sound produced by lightning, which heats its channel to about 54,000°F so the air expands explosively into a shock wave.
Thunder Bay 36 Fire
Thunder Bay 36 was a 2026 wildfire in northwestern Ontario and the largest ever recorded in Ontario, burning around Wabakimi Provincial Park and destroying Namaygoosisagagun First Nation.
Thundersnow
Thundersnow, also called a winter thunderstorm or thunder snowstorm, is snow falling at the surface together with lightning and thunder, a rare phenomenon that often marks bands of locally intense snowfall.
Thunderstorm
A thunderstorm, also known as a lightning storm, is a storm with lightning, thunder, and precipitation, formed from moisture, lifting air, and instability; about 16 million occur worldwide each year.
Thunderstorm electrification
Thunderstorm electrification is the process by which a storm cloud separates electric charge, mainly through collisions of ice crystals and graupel, building fields that produce lightning.
Tibetan Plateau heat low
The Tibetan Plateau heat low is the shallow surface low-pressure system that forms over the Tibetan Plateau in boreal summer, driven by heating of the elevated surface.
Ticsani
Ticsani is a dacitic lava dome complex in Moquegua region, southern Peru, 60 km NE of Moquegua city, 30 km SE of Huaynaputina. Last eruption about 1800 CE; fumarolic activity, recurring seismic swarms, high-risk classification, green alert, monitored by IGP and INGEMMET.
Tidal asymmetry
Tidal asymmetry is the inequality between the flood and ebb phases of a tidal cycle, arising when tidal waves distort in shallow water and shaping estuary sediment transport.
Tidal bore
A tidal bore, also called a mascaret or bore tide, is a moving wave that travels upstream when the rising tide enters a shallow, converging estuary, reaching up to 6 meters.
Tidal harmonic constants
Tidal harmonic constants (THCs) are the amplitude and phase lag of each tidal constituent at a location; once known, they let the tide be predicted far into the future.
Tidal prism
The tidal prism is the volume of tidal water exchanged between an estuary and the sea over one tidal cycle, a central quantity in estuarine hydrodynamics.
Tidal range
Tidal range is the vertical difference in height between consecutive high and low tides at a location, varying from centimeters on lakes to 16 meters in Canadian bays.
Tidal Waves
Tidal waves: the very long-period ocean waves caused by the Moon's and Sun's gravity, seen as tides; also a common but incorrect name for tsunamis, which are unrelated to tides.
Tide
The tide is the periodic rise and fall of sea level, caused by the gravitational pull of the Moon and Sun, giving coasts two high waters most days.
Tide gauge
A tide gauge, also called a mareograph, is an instrument that continuously records water level relative to a fixed land reference, supporting navigation, tsunami warning, and sea level studies.
Tide pool
A tide pool, also called a rock pool or tidal pool, is a pocket of seawater left in a rocky shore depression when the tide recedes, sheltering dense marine life.
Tide table
A tide table is a published or electronic listing of predicted times and heights of high and low water at a port, used by mariners and coastal engineers.
Tiger's eye
Tiger's eye is a golden-brown chatoyant gemstone of quartz whose parallel fibers produce a moving band of light; it is the most widely used cat's-eye gem in jewelry.
TIGGE
TIGGE, originally the THORPEX Interactive Grand Global Ensemble, is a multi-model archive of global ensemble weather forecasts from operational prediction centers, accumulating data since October 2006.
Tilocalar
Tilocalar (Tilocálar), a monogenetic volcanic field of four small andesitic centers in northern Chile's Salar de Atacama region, formed about 460–730 ka, with Tilocálar Norte and Sur erupting within 9 ± 2 kyr.
Tilt angle (potential-field method)
The tilt angle is an edge-detection filter for gravity and magnetic data, introduced by Miller and Singh in 1994, positive over a source and passing through zero at its edge.
Tiltmeter
A tiltmeter is a highly sensitive instrument that measures tiny changes in ground slope, used to monitor volcano deformation from moving magma, active faults, and dams.
Tim Samaras
Tim Samaras (1957–2013) was an American engineer and storm chaser who placed instrumented probes inside tornadoes; he died in the 2013 El Reno, Oklahoma tornado.
Time of concentration
The time of concentration is the time runoff takes to travel from a watershed's hydraulically most distant point to the outlet, a measure dating to 1851.
Time of Emergence
Time of emergence (ToE) is the time when an anthropogenic climate change signal emerges from natural climate variability in a given region, formalized by Ed Hawkins and Rowan Sutton in 2012.