Outdoor Glossary: P

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P - Rate of change (as of January 1, 1900) in mean longitude of lunar perigee. p = 0.004,641,83 per solar hour.

p1 - Rate of change (as of January 1, 1900) in mean longitude of solar perigee. p1 = 0.000,001,96 per solar hour.

P1 - Solar diurnal constituent. See K1. Speed = T - h = 14.958,931,4 per solar hour.

packcloth - A nylon fabric that combines a soft texture with rip resistance

palming - A technique used to slow down or put pressure on a hooked fish. It is accomplished by pressing the palm of your hand against the exposed reel spool as the fish is taking line

parallax - In tidal work, the term refers to horizontal parallax, which is the angle formed at the center of a celestial body between a line to the center of the Earth and a line tangent to the Earth's surface. It may also be expressed as an angle whose sine equals the Earth's radius divided by the distance of the celestial body, or, since the sine of a small angle is approximately equal to the angle itself in radians, it is usually taken in tidal work simply as the ratio of the mean radius of the Earth to the distance of the tide-producing body. Since the parallax is a function of the distance of a celestial body, the term is applied to tidal inequalities arising from the changing distance of the tide-producing body.

parallax inequality - The variation in the range of tide or in the speed of a tidal current due to changes in the distance of the Moon from the Earth. The range of tide and speed of the current tend alternately to increase and decrease as the Moon approaches its perigee and apogee, respectively, the complete cycle being the anomalistic month. There is a similar but relatively unimportant inequality due to the Sun, the cycle being the anomalistic year. The parallax has little direct effect upon the lunitidal intervals but tends to modify the phase effect. When the Moon is in perigee, the priming and lagging of the tide due to the phase is diminished and when in apogee the priming and lagging is increased.

parallax reduction - A processing of observed high and low waters to obtain quantities depending upon changes in the distance of the Moon, such as perigean and apogean ranges.

parallel plate intake - Intake of a stilling or protective well with two parallel plates attached below. The plates are typically three times the diameter of the well and are spaced three inches apart. The plates are used to minimize current-induced draw-down (Bernoulli effect) error in water level measurements.

parent material - The mineral or organic matter from which the upper layers of soil are formed.

park - like structure- Stands with large scattered trees and open growing conditions, usually maintained by ground fires.

partial retention - A visual quality objective which, in general, means man's activities may be evident but must remain subordinate to the characteristic landscape.

partially mixed estuary - An ESTUARY that shows a small to moderate salinity change with DEPTH.

Particle size - in dealing with sediments and sedimentary rocks it is necessary that precise dimensions should be applied to such terms as CLAY, sand, pebble, etc. Numerous scales have been suggested, but in this work, the Wentworth-Udden scale is used, as it is widely accepted as an international standard. In the table which follows, particle size limits are shown, but within most groups further subdivision is possible; for example, sand may be described as very fine, medium, coarse, very coarse. particle size is normally determined by hand measurement of pebbles, cobbles, and BOULDERS, sieving of GRAVEL, sand and silt and ELUTRIATION of silt and CLAY (7). Size Range Particle >256 mm. BOULDER 64 256 mm. Cobble 4 64 mm. Pebble 2 4 mm. Granule, gravel 1/16 2 mm. Sand 1/256 1/16 mm. Silt <1/256 mm. CLAY

patagial mark - Dark patch on leading edge of underside of inner wing.

patch - An area of homogeneous vegetation, in structure and composition.

patch cut - A clearcut that creates small openings in a stand of trees, usually between 15 and 40 acres in size. On the Dixie National Forest and elsewhere, patchcuts are used to provide the disturbance needed to regenerate aspen.

peak period - The wave period determined by the inverse of the frequency at which the wave energy spectrum reaches its maximum.

pebbles - Beach material usually well-rounded and between about 4 mm to 64 mm diameter.

pelagic - Living on the open ocean rather than coastal or inland bodies of water

pelorus - An instrument used on a vessel in connection with a current line and current pole to obtain the set of the current. In its simplest form, it is a disk about 8 inches in diameter and graduated clockwise for every 5 or 10. It is mounted rigidly on the vessel, usually with the 0 mark forward and the diameter through this mark parallel with the keel. Bearings are then related to the vessel's compass and converted to true.

peninsula - An elongated portion of land nearly surrounded by water and connected to a larger body of land, usually by a NECK or an ISTHMUS.

percolation - Downward flow or infiltration of water through the pores or spaces of rock or soil.

perennial stream - A stream that flows throughout the year and from source to mouth.

Perigean range - The average semidiurnal range occurring at the time of the PERIGEAN TIDES and most conveniently computed from the harmonic constants. It is larger than the mean range where the type of tide is either semidiurnal or mixed and is of no practical significance where the type of tide is DIURNAL.

perigean tides or tidal currents - Tides of increased range or tidal currents of increased speed occurring monthly as the result of the Moon being in perigee. The perigean range (Pn) of tide is the average range occurring at the time of perigean tides and is most conveniently computed from the harmonic constants. It is larger than the mean range where the type of tide is either semi diurnal or mixed, and is of no practical significance where the type of tide is predominantly diurnal.

perigee - The point in the orbit of the Moon or man-made satellite nearest to the Earth. The point in the orbit of a satellite nearest to its companion body.

perihelion - The point in the orbit of the Earth (or other planet, etc.) nearest to the Sun.

period - Interval required for the completion of a recurring event, such as the revolution of a celestial body or the time between two consecutive like phases of the tide or tidal current. A period may be expressed in A angular measure and is then taken as 360. The word also is used to express any specified duration oftime.

periodic current - A current caused by the tide-producing forces of the Moon and the Sun, a part of the same general movement of the sea that is manifested in the vertical rise and fall of the tides. See FLOOD CURRENT and EBB CURRENT.

permanent current - A current that runs continuously independent of the tides and temporary cause. Permanent currents include the fresh water discharge of a river and the currents that form the general circulatory systems of the ocean.

permeability - The property of bulk material (sand, crushed rock, soft rock in situ) which permit movement of water through its pores.

permeable groin - A GROIN with openings large enough to permit passage of appreciable quantities of LITTORAL DRIFT.

permitted grazing - Grazing on a National Forest range allotment under the terms of a grazing permit.

personal floation device - (PFD) - A life vest/preserver

personal use - The use of a forest product, such as firewood, for home use and not for commercial use.

Peru Current - A South Pacific Ocean current setting northward along the west coast of South America. It has sometimes been called the Humboldt Current because an early record of its temperature was taken by the German scientist Alexander von Humboldt in 1802. It has also been called the Peruvian or Chilean Current. The name Corriente de Peru was adopted by a resolution of the Ibero-American Oceanographic Conference at its Madrid-Malaga meeting in April 1935.

petrology - That branch of GEOLOGY which treats of the scientific study of rocks.

pH meter - The measurement of the amount of acidity and/or alkalinity of water on a scale of 0 to 14. Water with a pH less than 7 is acidic and more than 7 is basic.

phase - (1) Any recurring aspect of a periodic phenomenon, such as new Moon, high water, flood strength, etc. (2) A particular instant of a periodic function expressed in angular measure and reckoned from the time of its maximum value, the entire period of the function being taken as 360. The maximum and minimum of a harmonic constituent have phase values of 0 and 180, respectively.

phase inequality - Variations in the tides or tidal currents due to changes in the phase of the Moon. At the times of new and full Moon the tide-producing forces of the Moon and Sun act in conjunction, causing the range of tide and speed of the tidal current to be greater than the average, the tides at these times being known as spring tides. At the times of the quadratures of the Moon these forces are opposed to each other, causing neap tides with diminished range and current speed.

phase lag - Same as epoch (1).

phase reduction - A processing of observed high and low waters to obtain quantities depending upon the phase of the Moon, such as the spring and neap ranges of tide. At a former time this process was known as second reduction. Also applicable to tidal currents.

photic zone - The zone extending downward from the ocean surface within which the light is sufficient to sustain photosynthesis. The DEPTH of this layer varies with water clarity, time of year and cloud cover, but is about 100 m in the open ocean. It may be considered the DEPTH to which all light is filtered out except for about one percent and may be calculated as about two and one-half times the DEPTH of a SECCHI DISK reading.

photogrammetry - The science of deducing the physical dimensions of objects from measurements on images (usually photographs) of the objects.

photomosaic - An assemblage of photographs, each of which shows part of a region, put together in such a way that each point in the region appears once and only once in the assemblage, and scale variation is minimized.

physical geology - A large division of GEOLOGY concerned with earth materials, changes of the surface and interior of the earth, and the forces that cause those changes.

Pier - A structure, usually of open construction, extending out into the water from the shore, to serve as a landing place, recreational facility, etc., rather than to afford coastal protection.

pile - A long substantial pole of wood, concrete or metal, driven into the earth or sea bed to serve as a support or protection.

pileum - Top of the head extending from the base of the bill to the nape

piling, sheet - Interlocking member of wood, steel, concrete, etc., subject to lateral pressure, driven individually to form an obstruction to percolation, to prevent movement of material for seawalls, stabilization of foundations, etc.

pinnae - Projecting feathers.

piping - EROSION of closed flow CHANNELS (tunnels) by the passage of water through soil; flow underneath structures, carrying subsoil particles, may endanger the stability of the structure.

pistol - A specialty grip that enables an angler to make much more compact and accurate casts.

pitching precision - casting done with an underhand pendulum motion

pixel - An element of surface resulting from subdividing an image into the smallest identically shaped figures that give information about the location, intensity and perhaps color of the source, but such that no smaller subdivision will provide more information.

Placer deposits - MINERAL deposits consisting of dense, resistant and often economically valuable minerals which have been weathered from TERRIGENOUS ROCKS, transported to the sea and concentrated in marine sediments by wave or current action.

placer mine - Surface mines in which valuable MINERAL grains are extracted from stream bar or beach deposits.

Planform - The outline or shape of a body of water as determined by the stillwater line.

planning area - The area of National Forest land covered by a Regional Guide or Forest Plan.

planning period - The 50 year time frame for which goods, services, and effects were projected in the development of the Forest Plan.

plateau - (1) (Geographical) an elevated plain, tableland or flat-topped region of considerable extent. (2) (Oceanographical) an ELEVATION from the bottom of the ocean with a more or less flat top and steep sides.

pleistocene - An epoch of the Quaternary Period characterized by several glacial ages.

PLSS - Public Land Survey System. The U.S. Public Land Survey System is the most widespread land ownership system in the United States. Land is subdivided by a rectangular system of surveys established and regulated by the Bureau of Land Management. The standard format for subdivision is based on townships measuring 6 miles (480 chains) on a side. Townships are further subdivided into 36 numbered sections of 1 square mile (640 acres) each.
plumes - Large, conspicuous, showy, feathers.

plunge point - (1) For a PLUNGING WAVE, the point at which the wave curls over and breaks. (2) The final breaking point of the waves just before the water rushes up the BEACH.

PNV - See present net value.

pocket beach - A BEACH, usually small, between two headlands.

point - The sharp end of a hook

point - (1) The extreme end of a CAPE, or the outer end of any land area protruding into the water, usually less prominent than a CAPE. (2) (SMP) A low profile SHORELINE PROMONTORY of more or less triangular shape, the top of which extends SEAWARD.

point bar - A stream bar deposited on the inside of a curve in the stream, where the water velocity is low.

pole - A 4-letter word for a fly rod

pole timber - Trees at least 5 inches in diameter, but smaller than the minimum size for sawtimber.

pole/sapling - The stage of forest succession in which trees are between 3 and 7 inches in diameter and are the dominant vegetation.

polygyny - a mating system in which successful males mate with more than one female.

poppers - These baits are great topwater lures,and can call up fish from some really long distances. They can be worked in a steady relatively fast retrieve, or jerked and made to splash and spit in one place for quite some time.

popping reel - A reel that is used to present an artificial bait lure that makes sounds to attract fish.

population - a biologically, geographically, or politically defined group of animals composed of all of the individuals of a species in a particular area.

population dynamics - the study of changes in the number and composition of individuals in a population, and the factors that influence those changes.

pororoca - Brazilian for tidal bore.

port - A place where vessels may discharge or receive cargo.

PORTS - Physical Oceanographic Real Time System. A system of current, water level, and meteorological stations telemetering their data to a central location for storage, processing, and dissemination. Available to pilots, mariners, the U.S. Coast Guard, and other marine interests in voice or digital real-time form. First introduced in Tampa Bay.

potential, tide-producing - Tendency for particles on the Earth to change their positions as a. result of the gravitational interactions between the Sun, Moon, and Earth. Although the gravitational attraction varies inversely as the square of the distance of the tide producing body, the resulting potential varies inversely as the cube of the distance.

poultry - domestic species raised primarily for food and fiber; chickens, domestic ducks and geese, and common turkeys.

pre - existing use- Land use that may not conform to a zoning ordinance but existed prior to the enactment of the ordinance.

precommercial thinning - Removing some of the trees from a stand that are too small to be sold for lumber or house logs, so the remaining trees will grow faster.

predator - an animal that hunts and kills other animals for food. The red fox is a predator that feeds on mice, rabbits, and other small animals. Predators are at or near the tops of food chains.

predicting machine - See tide predicting machine. pressure gauge A tide gauge that is operated by the change in pressure at the bottom of a body of water due to the rise and fall of the tide. See gas purged pressure gauge.

preparatory cut - The removal of trees near the end of a rotation to open the canopy so the crowns of seed bearing trees can enlarge. This improves seed production and encourages natural regeneration. (See rotation.)

prescribed fire - Fire set intentionally in wildland fuels under prescribed conditions and circumstances. Prescribed fire can rejuvenate forage for livestock and wildlife or prepare sites for natural regeneration of trees.

prescription - Management practices selected to accomplish specific land and resource management objectives.

present net value (PNV), also called present net worth - The measure of the economic value of a project when costs and revenues occur in different time periods. Future revenues and costs are "discounted " to the present by an interest rate that reflects the changing value of a dollar over time. The assumption is that dollars today are more valuable than dollars in the future. PNV is used to compare project alternatives that have different cost and revenue flows.

presentation - The process of "presenting" a fly to a fish; includes the manner in which the cast is delivered, the line is mended and the fly is fished

preservation - the protection of a resource by withdrawing it from use.

preservation - Static protection of an area or element, attempting to perpetuate the existence of a given 'state'.

pressure gradient force, horizontal - The horizontal component of the product of the specific volume and the rate of decrease in pressure with distance.

pressure sensor - A pressure transducer sensing device for water level measurement. A relative transducer is vented to the atmosphere and pressure readings are made relative to atmospheric pressure. An absolute transducer measures the pressure at its location. The readings are then corrected for barometric pressure taken at the surface.

presuppression - Activities carried out in advance of fire occurrence to ensure effective suppression when the need arises.

prey - 1. Animals eaten by predatory animals. A mouse is prey for a fox. 2. To capture and devour an animal. The fox preys on mice.

primaries - Flight feathers attached to the "hand".

primary control tide station - A tide station at which continuous observations have been made over a minimum of 19 years. Its purpose is to provide data for computing accepted values of the harmonic and non harmonic constants essential to tide predictions and to the determination of tidal datums for charting and for coastal and marine boundaries. The data series from this station serves as a primary control for the reduction of relatively short series from subordinate tide stations through the method of comparison of simultaneous observations and for monitoring long-period sea level trends and variations. See tide station, secondary control tide station, tertiary tide station, and subordinate tide station (1).

primary coverts - Feathers protecting and covering the primaries.

primary numbering - system for assigning a number to each primary.

primary tidal bench mark - See bench mark.

prime meridian - The meridian of longitude which passes through the original site of the Royal Observatory in Greenwich, England and used as the origin of longitude. Also known as the Greenwich Meridian.

priming of tide - The periodic acceleration in the time of occurrence of high and low waters due to changes in the relative positions of the Sun and Moon.

primitive ROS (Recreation Opportunity Spectrum) - A classification of wilderness and recreation opportunity. It is characterized by an essentially unmodified environment, where trails may be present but structures are rare, and where it is highly probable to be isolated from the sights and sounds of people. (See ROS.)

productive - The ability of an area to provide goods and services and to sustain ecological values.

profile, beach - See BEACH PROFILE

prognosis - A computer model for timber growth and yield. It projects per-acre growth and volume yield for commercial timber stands.

progressive wave - A wave that advances in distance along the sea surface or at some intermediate depth. Although the wave form itself travels significant distances, the water particles that make up the wave merely describe circular (in relatively deep water) or elliptical (in relatively shallow water) orbits. With high, steep, wind waves, a small overlap in the orbital motion becomes significant. This overlapping gives rise to a small net mass transport. See long shore current and rip current. Progressive waves can be internal, traveling along a sharp density discontinuity, such as the thermocline, or in an area of gradually changing density (vertically).

promontory - A high point of land extending into a body of water; a HEADLAND.

protective well - A vertical pipe with a relatively large opening (intake) in the bottom. It is used with the air acoustic ranging sensor and electronic processing (filtering) technique to minimize the nonlinear characteristics of the stilling well. Its purpose is also to shield the sensing element from physical damage and harsh environment. Unlike a stilling well, damping of high frequency waves is not a critical requirement. See stilling well.

public domain - The territory ceded to the Federal government by the original thirteen states, plus additions by treaty, cession, and purchase.

public involvement - The use of appropriate procedures to inform the public, obtain early and continuing public participation, and consider the views of interested parties in planning and decision making.