Weather terms starting with P

261 terms

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Pacific Decadal Oscillation (Abbrev. PDO) - a recently described pattern of climate variation similar to ENSO though on a timescale of decades and not seasons.
paleoclimate past or ancient climates.
paleoclimatologist one who studies ancient (paleo-) climate.
paleoenvironmental proxy an environmental relict (pollen grains, tree rings, lake sediments, pack rat middens, ice cores, coral skeletons) that is used by scientists to infer past…
Palmer Drought Severity Index An index whereby excesses or deficiencies of precipitation are determined in relation to average climate values.
Pan Pan A headline within National Weather Service high seas forecasts transmitted via the GMDSS to indicate that a hurricane or hurricane force winds are…
Pancake Ice Circular flat pieces of ice with a raised rim; the shape and rim are due to repeated collisions.
Panhandle Hook Low pressure systems that originate in the panhandle region of Texas and Oklahoma which initially move east and then "hook" or recurve more northeast…
parameter A value or measurement that varies with circumstances, and is used as a reference to quantify a situation or a process.
Parapet Wall A solid wall built along the top of a dam (upstream and/or downstream edge) used for ornamentation, for safety of vehicles and pedestrians, or to prevent…
Parcel A volume of air small enough to contain uniform distribution of its meteorological properties and large enough to remain relatively self-contained and…
Parhelion The scientific name for sun dogs. Either of two colored luminous spots that appear at roughly 22 degrees on both sides of the sun at the same elevation.
Partial Beam Filling A limitation of the rainfall estimation techniques used by NEXRAD. At far ranges from the radar, a storm may occupy only a portion of the radar beam…
Partial-Duration Flood Series A list of all flood peaks that exceed a chosen base stage or discharge, regardless of the number of peaks occurring in a year.
particle number concentration The number of particles present in any given volume of air.
particle size distribution The number of particles present in any given volume of air within a specified size range.
Particle Trajectory Model A computer sub-model that tracks the trajectories of multiple particles that are released into an atmospheric flow model.
Particulate A small, discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions.
Particulate Matter (PM) Very small pieces of solid or liquid matter such as particles of soot, dust, fumes, mists or aerosols.
Particulates The fine liquid or solid particles contained in combustion gases. The quantity and size of particulates emitted by cars, power and industrial plants, wood…
Partly Cloudy Between 3/8 and 5/8 of the sky is covered by clouds.
Partly Sunny Between 3/8 and 5/8 of the sky is covered by clouds. The term "Partly Sunny" is used only during daylight hours.
Parts per billion (ppb) A measurement of concentration on a weight or volume basis. Equivalent to micrograms per liter.
Parts per million (ppm) A measurement of concentration on a weight or volume basis. Equivalent to milligrams per liter (mg/l).
Pascal The unit of pressure produced when one newton acts on one square meter (1 N/m2). It is abbreviated Pa.
Past weather Past weather Predominant characteristic of the weather which had existed at an observing station during a given period of time (during the preceding hour…
PAT In blackjack, an unbusted hand worth at least 17 points. In draw poker, a hand that does not need any more hands.
PBL Probable
PC-GRIDDS PC-Gridded Interactive Display and Diagnostic System - Allows the forecaster to view fields of gridded model output in contour or vector format.
PCPN Precipitation
PCT Patent Cooperation Treaty (more) provides a mechanism by which an applicant can file a single application that, when certain requirements have been…
PD Period
PDI Palmer Drought Index
PDMT Predominant
PDO Pacific Decadal Oscillation - a recently described pattern of climate variation similar to ENSO though on a timescale of decades and not seasons.
PDS Particularly Dangerous Situation (PDS) wording is used in rare situations when long-lived, strong and violent tornadoes are possible.
PDS Watch The Particularly Dangerous Situation (PDS) wording is used in rare situations when long-lived, strong and violent tornadoes are possible.
PDSI Palmer Drought Severity Index - an index used to gage the severity of drought conditions by using a water balance equation to track water supply and…
PDT Pacific Daylight Time
Peak Discharge Highest rate of discharge of a volume of water passing a given location during a given period of time (during the year, or a flood event, etc..).
Peak Gust The highest instantaneous wind speed observed or recorded.
Peak Pulse The amount of power transmitted by a radar during a given pulse. Note that because these pulses are widely spaced, the average power will be much smaller.
Peak Wind Speed The maximum instantaneous wind speed (or velocity) that occurs within a specific period of time or interval.
Pendant Echo Radar signature generally similar to a hook echo, except that the hook shape is not as well defined.
Penetrating Top Same as Overshooting Top; a dome-like protrusion above a thunderstorm anvil, representing a very strong updraft and hence a higher potential for severe…
Pentanes plus A mixture of hydrocarbons, mostly pentanes and heavier fractions, extracted from natural gas. See hydrocarbons.
Penumbra In solar-terrestrial terms, the sunspot area that may surround the darker umbra or umbrae.
Perched Groundwater Local saturated zones above the water table which exist above an impervious layer of limited extent.
Percolation The filtering of a liquid passed through a medium with many fine spaces.
Percolation Path The course followed by water moving or percolating through any other permeable material, or under a dam which rests upon a permeable foundation.
Perennial Stream A stream that flows continually throughout the year.
Perfluorocarbons (PFCs) A group of human-made chemicals composed of carbon and fluorine only. These chemicals (predominantly CF4 and C2F6) were introduced as alternatives, along…
Perigee The closest distance between moon and earth or the earth and sun.
Perihelion The point on the annual orbit of a body (about the sun) that is closest to the sun; at present, the earth reaches this point on about 5 January.
Permafrost Perennially frozen soil.
Permeability The rate at which liquids pass through soil or other materials in a specified direction.
Permeability Coefficient The rate of flow of a fluid through a cross section of a porous mass under a unit hydraulic gradient, at a temperature of 60 degrees Fahrenheit.
Permeameter Device for containing the soil sample and subjecting it to fluid flow in order to measure permeability or hydraulic conductivity.
persistence Ability of an organism to remain in a particular setting for a period of time after it is introduced.
Persistence Forecast A forecast that the current weather condition will persist and that future weather will be the same as the present (e.g.
Perturbation Model A computer model used to calculate air pollution concentrations. A perturbation model produces a wind field from solutions to a simplified set of…
Pervious Zone A part of the cross section of an embankment dam comprising material of high permeability.
Petrochemical feedstock Feedstock derived from petroleum, used principally for the manufacture of chemicals, synthetic rubber, and a variety of plastics.
Petrochemicals Chemicals obtained by refining (i.e., distilling) crude oil. They are used as raw materials in the manufacture of most industrial chemicals, fertilizers…
Petroleum Any petroleum-based substance composed of a complex blend of hydrocarbons derived from crude oil, including motor fuel, jet oil, lubricants, petroleum…
Petroleum coke A residue that is the final product of the condensation process in cracking.
PFD A personal flotation device or life jacket.
Phenomenological Model A computer model used to calculate air pollution concentrations. A phenomenological model focuses on an individual phenomenon, such as plume impingement…
Phiezometer In hydrologic terms, an instrument used to measure pressure head in a conduit, tank, soil, etc. They are used in dams to measure the level of saturation.
Photochemical Smog Air pollution containing ozone and other reactive chemical compounds formed by the reaction of nitrogen oxides and hydrocarbons in the presence of…
Photosphere The Sun’s surface, from which the light we actually see (with the human eye) is emitted. Temperatures average 5,800 K (9,900°F).
Photosynthesis A chemical process by which green plants synthesize organic compounds from carbon dioxide and water in the presence of sunlight.
Photovoltaic and solar thermal energy Energy radiated by the sun as electromagnetic waves (electromagnetic radiation) that is converted into electricity by means of solar (i.e.
Phreatic water Water within the earth that supplies wells and springs; water in the zone of saturation where all openings in rocks and soil are filled, the upper surface…
PIBAL Pilot balloon. A small helium-filled meteorological balloon that is tracked as it rises through the atmosphere to determine how wind speed and direction…
Pilot Balloon (Abbrev. PIBAL)- A small helium-filled meteorological balloon that is tracked as it rises through the atmosphere to determine how wind speed and direction…
Pilot Report (Abbrev. PIREP)- A report of inflight weather by an aircraft pilot or crew member.
Pingo A large frost mound of more than one-year duration.
PIREP Pilot Report. A report of inflight weather by an aircraft pilot or crew member.
Pitot Tube A device for measuring the velocity of flowing water using the velocity head of the stream as an index of velocity.
PIX picture
PK Player Kill or Player Killer.
PL Ice pellets (sleet)
Plage In solar-terrestrial terms, an extended emission feature of an active region that exists from the emergence of the first magnetic flux until the widely…
Plage Corridor In solar-terrestrial terms, a space in chromospheric plage lacking plage intensity, coinciding with polarity inversion line.
Plagenil In solar-terrestrial terms, spotless disc free of calcium plage.
Plan Position Indicator An acronym for Plan Position Indicator. A PPI displays radar data horizontally using a map projection.
Planetary Boundary Layer The layer within the atmosphere between 1 km and the earth's surface where friction affects wind speed and wind direction.
Plankton Collectively, all organisms (plants and animals) suspended in the water which are not independent of water movements.
planktonic foraminifera Marine zooplankton that passively float or weakly swim, and have calcium carbonate skeletons that are present in large numbers on the surface of the ocean.
Plasma (PLAZ-muh) The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.
platform A generic radar term, often used to encompass the pedestal and antenna assembly; sometimes including the radar control, display and analysis hardware and…
Pleistocene epoch An interval of the Quaternary period, from 1.8 million to about 11,500 years before present.
Plow Wind A term used in the midwestern United States to describe strong, straight-line winds associated with the downdrafts spreading out in advance of squall…
Plume Blight Visibility impairment caused by air pollution plumes aggregated from individual sources.
Plume Impingement The collision of a plume with topography that rises above the plume altitude; often a temporary condition that occurs as the plume sweeps by the face of a…
Plume-dominated Fire A fire whose behavior is governed primarily by the local wind circulation produced in response to the strong convection above the fire rather than by the…
Pluvial In hydrology, anything that is brought about directly by precipitation.
PMD Prognostic Discussion