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Panta Rhei (hydrology)
Panta Rhei, Greek for "everything flows," was the second Scientific Decade of the International Association of Hydrological Sciences, running from 2013 to 2022 to study change in hydrology and society.
Paracelsian
Paracelsian is a rare barium feldspar mineral, the dimorph of celsian, first described in 1905 from Candoglia, Italy, and best known from the Benallt Mine in Wales.
Parachute Creek
Parachute Creek is a stream in Garfield County, Colorado, whose name is attached to the Parachute Creek Member, the Green River Formation's oil shale unit, and Unocal's project there.
Parasequence
A parasequence is a relatively conformable succession of genetically related beds bounded by marine flooding surfaces, recording one episode of shoreline progradation, introduced by Van Wagoner and colleagues in the 1980s.
ParFlow
ParFlow (PARallel FLOW) is an open-source, parallel, integrated hydrology model that simulates surface and subsurface water flow with land surface processes, initiated at Lawrence Livermore National Laboratory in the mid-1990s.
Parícutin
Parícutin is a volcano in Michoacán, Mexico, that erupted from 1943 to 1952 after being born in a farmer's cornfield, and no one died directly from it.
Parshall flume
The Parshall flume is an open-channel flow-measuring structure invented by Ralph Parshall in 1922, which converts upstream water depth into discharge and is widely used for irrigation and wastewater.
Partial melting
Partial melting, also called anatexis, is the transformation of part of a solid rock into liquid magma, caused by decompression, heat input, or added water rather than complete melting.
Pascua-Lama
Pascua-Lama is a binational gold-silver-copper mining project straddling the Chile-Argentina border in the Andes above 4,500 meters, developed by Barrick Gold and definitively closed in 2020.
Passive margin
Passive margin is a tectonic transition between continental and oceanic crust, forming where a continent rifted apart, such as along the Atlantic coast of North America.
Passive seismology
Passive seismology is the imaging of Earth's subsurface using natural seismic sources, earthquakes and ambient noise, instead of controlled artificial sources, at much lower cost.
Patricia Dalyander
Patricia ("Soupy") Dalyander is an American physical oceanographer known for modeling how waves and currents move sand, oil, and barrier islands along the Gulf of Mexico coast, and a 2019 PECASE recipient.
Pattern scaling
Pattern scaling is a climate-modeling approximation in which the regional pattern of climate change is assumed constant and scaled linearly with global mean warming, first proposed by Santer et al. in 1990.
Patterned ground
Patterned ground is ground displaying regular geometric shapes such as circles, polygons, nets, steps, and stripes, produced by frost action in cold climates; similar polygons also occur on Mars.
Pavonis Mons
Pavonis Mons, Latin for peacock mountain, is the central and smallest of the three Tharsis Montes shield volcanoes on Mars, about 14 km high, 375 km wide, straddling the equator, with nested summit calderas and lava tubes.
Payun Matru
Payún Matrú (Payun Matru), a Quaternary shield volcano with an 8-10 km summit caldera in Mendoza, Argentina, center of the 5,200 km² Payún Matrú volcanic field, source of Earth's longest known Quaternary lava flow.
PCR-GLOBWB
PCR-GLOBWB (PCRaster Global Water Balance) is an open-source global hydrology and water resources model developed at Utrecht University in the Netherlands, simulating soil moisture, groundwater, and human water use at daily time steps.
Pea soup fog
Pea soup fog, or pea-souper, is a thick yellowish or blackish fog colored by coal soot and sulfur dioxide, typified by London's fogs and the Great Smog of December 1952; the name comes from split-pea soup.
Peak ground acceleration
Peak ground acceleration, or PGA, is the largest ground acceleration recorded at a point during an earthquake, usually expressed as a percentage of the acceleration of gravity, g.
Peak water
Peak water is the concept that freshwater availability or use can rise to a maximum and then decline, formalized by Peter Gleick and Meena Palaniappan in 2010.
Peat subsidence
Peat subsidence is the lowering of the land surface when drained peat soils shrink, consolidate, compact, and oxidize, typically at rates of millimeters to centimeters per year.
Peatland rewetting
Peatland rewetting is the cessation of drainage and restoration of high groundwater levels in degraded peatlands, typically by ditch blocking, to stop carbon dioxide emissions from dried-out peat soils.
Pebble
A pebble is a small rock fragment, 4 to 64 mm in diameter, rounded by stream or wave transport; its size and shape record how far it traveled.
Pedotransfer functions
Pedotransfer functions are mathematical models, typically regressions or machine learning, that estimate hard-to-measure soil hydraulic properties from routinely available data like texture and bulk density.
Pegmatite
Pegmatite is a coarse-grained igneous rock composed largely of granite minerals such as quartz, feldspar, and muscovite, mined for rare elements like lithium and tantalum, and for gemstones.
Pelagic zone
The pelagic zone, also called the open ocean, is the entire water column of the sea, away from the bottom and shore, and Earth's largest habitat.
Peñasquito mine
Peñasquito is a polymetallic open-pit mine in Mazapil, Zacatecas, Mexico, producing gold, silver, lead, and zinc since 2009. Owned by Newmont, it is Mexico's largest gold mine.
Penetrative convection
Penetrative convection is a form of turbulent convection in which surface cooling drives plumes that overshoot into stratified water below, entraining it and deepening a lake's mixed layer.
Penman–Monteith equation
The Penman–Monteith equation estimates evapotranspiration from standard weather variables, combining surface energy balance with aerodynamic vapor transfer; FAO-56 adopted it as its sole standard in 1998.
Pennsylvanian (geology)
The Pennsylvanian, or Pennsylvanian Period, is the younger half of the Carboniferous Period, from 323.2 to 298.9 million years ago, named for Pennsylvania's coal-bearing rocks.