Earth sciences

Rapid Update Cycle

The Rapid Update Cycle (RUC) was a NOAA numerical weather prediction system that produced hourly analyses and short-range forecasts over the US from 1994 to 2012.

Rasputitsa (распу́тица), also bezdorozhye/bezdorizhzhia, is the twice-yearly spring-thaw and autumn-rain mud season of Russia, Belarus, and Ukraine, when unpaved roads become impassable; it shaped Napoleon's 1812 retreat and WWII Eastern Front operations.

Rating curve

A rating curve is the empirical relation between water level and discharge at a stream gauging station, used to turn continuous stage records into continuous river discharge records.

Rational method (hydrology)

The rational method is an empirical hydrology formula, developed by Thomas Mulvany in 1850, that estimates peak runoff as the product of drainage area, runoff coefficient, and rainfall intensity.

Ravi River

The Ravi River, known in Vedic Sanskrit as Parushni and to Greek writers as Hydraotes, is a transboundary river of the Indus basin and one of the five rivers of the Punjab.

Raygorodok Gold Mine

The Raygorodok Gold Mine is an open-pit gold mine in northern Kazakhstan's Akmola Region and one of the country's largest single gold deposits, with 194.2 tonnes of contained gold.

Rayleigh wave tomography

Rayleigh wave tomography is a seismological imaging method that measures Rayleigh wave dispersion along earthquake–station paths and inverts it for 3-D shear-wave velocity models of the crust and upper mantle.

Rb–Sr dating

Rb–Sr dating is a radiometric method that determines geological ages by measuring the decay of radioactive rubidium-87 into strontium-87, dating igneous crystallization, metamorphic events, or a rock's last heating.

Reactive transport model

A reactive transport model is a numerical model that couples fluid flow, solute transport, and chemical reactions in porous or fractured subsurface media, applied to CO₂ storage and remediation.

Realgar

Realgar is a red to orange-red arsenic sulfide mineral and a principal ore of arsenic, occurring in low-temperature hydrothermal veins and historically used as a pigment.

Rear-inflow jet

A rear-inflow jet (RIJ) is a layer of cool, dry air that enters a mesoscale convective system from the rear, descending toward the leading line of storms.

Receiver function

A receiver function is a time series computed from teleseismic seismograms by deconvolution, imaging crustal and upper-mantle discontinuities such as the Moho beneath a seismic station.

Red Chris mine

Red Chris is a copper and gold mine in the Golden Triangle of northwest British Columbia, Canada, which began production in 2015 and is operated by Newmont.

Red Dog Mine

The Red Dog Mine is one of the world's largest zinc mines, an open-pit operation in the De Long Mountains of northwest Alaska producing zinc and lead since 1989.

Red flag warning

A red flag warning is a National Weather Service alert that critical fire weather conditions, such as strong wind and very low humidity, are occurring or expected within about a day.

Oct 21, 2026

Red Hill-Quemado

Red Hill-Quemado volcanic field (Quemado volcanic field): basaltic monogenetic field in Catron County, western New Mexico, on the Jemez lineament, with 40+ cinder cones and maars active from about 8 Ma to the early Holocene, including Zuni Salt Lake maar.

Red rain in Kerala

The red rain in Kerala, or Kerala red rain phenomenon, was a series of red rain events that began in Kerala, India, on 25 July 2001.

Red Sea

The Red Sea is a long, narrow ocean basin between northeastern Africa and the Arabian Peninsula, among the world's warmest and saltiest seas and a critical global shipping route.

Red sky at morning

"Red sky at morning" is the warning half of the weather proverb "Red sky at night, sailors' delight", a forecasting rule of thumb with a real basis.

Red soil

Red soil is soil colored red or brownish red by iron oxides, chiefly hematite, that forms in hot, humid climates and supports much tropical agriculture.

Redoxcline

A redoxcline is the layer in a lake or basin where redox conditions change sharply with depth, separating oxygenated water above from anoxic water or sediment below.

Reducing emissions from deforestation and forest degradation (REDD+)

REDD+ is a UNFCCC framework under which developing countries receive results-based payments for verified emission reductions from reducing deforestation and forest degradation, plus conservation and sustainable management of forests.

Reed Timmer

Reed Timmer is an American extreme meteorologist and storm chaser known for driving armored vehicles into tornadoes and starring in the Discovery Channel series Storm Chasers.

Reference conditions (Water Framework Directive)

Reference conditions under the EU Water Framework Directive are the near-natural values for surface water quality elements, serving as the benchmark for classifying high ecological status.

Reflection seismology

Reflection seismology, also called seismic reflection, is a geophysical method that maps subsurface rock layers from reflected seismic waves and is the petroleum industry's principal imaging tool.

Refractory dissolved organic carbon

Refractory dissolved organic carbon, or rDOC, is the ocean's dissolved organic carbon that resists microbial degradation, persisting for millennia and totaling about 640 Pg C.

Regional climate model

A regional climate model (RCM) is a limited-area atmospheric model driven at its edges by a global climate model, downscaling coarse global projections into regional detail for climate studies.

Regional Greenhouse Gas Initiative

The Regional Greenhouse Gas Initiative (RGGI) is a cooperative cap-and-invest program of eleven U.S. states that caps and reduces carbon dioxide emissions from the electric power sector.

Regional impacts of climate change

Regional impacts of climate change are the effects of global warming on particular regions, which differ sharply, with the Arctic warming fastest and low-lying coasts hit hardest.