"P"

Palmer Drought Severity Index: Index used to tel the severity of drought conditions .
Parameter: Elements which make up a weather observation such as present weather/visibility/temperature/pressure, etc.
Parcel: A small volume of air.
Partial Obscuration: When parts of the sky are hidden from surface based: Smoke: Fog: Snow: Rain: Etc.
Partly Sunny: 3/8 to 1/2 sky coverage.
Peak Gust: Highest instantaneous wind speed.
Peak Gust Recorder: A weather instrument which measures and records the peak wind speed.
Peak Wind Speed: The highest wind speed observed.
Penumbra: Lighter protion of "Sunspots" with temperatures about 5,400 degs. Kelvin.
Perihelion: The time of the year when the Earth is closest to the Sun, (About Jan. 4).
PH Scale: A scale which measures the amount of alkalinity or acidity of different substances. The PH of pure distilled water is 7.0
Photosphere: The surface of the sun.

Photosynthesis: When plants use sunlight, water and Carbon Dioxide (CO2) to manufacture their food the waste product produced is (Oxygen).
Pibal: - "Pilot Balloon" "sent aloft to determine the wind speed & direction up to 60,000+ feet which is than tracked with a "Theodolite".
PIREP: Acronym for: Pilot Weather Report".
Plan Position Indicator: (PPI) A radar monitor scope which displays the location of precipitation using the range in miles and degrees in azimuth.
Planetary Weather Systems: Northeast & Southeast Trade Winds located at 0 Degs. - 30 Degs. N. & S. Latitudes. Westerlies at 30-60 Degs. N. & S. Latitudes. Polar Northeasterlies at 60 Degs. to 90 Degs. N. Lat. Polar Southeastlies at 60 Degs.- 90 Degs S. Lat.
PM: Post Meridiem Time: Between Noon and Midnight.
Polar Easterlies: Located at 60 - 90 degs. North Latitude.
Polar Front: Located along the northerly jet stream.
Pollution: Anything that contaminates or alters the normal structure of the component such as: Water Pollution: Air Pollution: Ground Pollution:
Potential Energy: Something that can do work such as a train locomotive.
PPM:Parts Per Million.
Precipital Water: Amount of water in a vertical column of atmosphere.
Precipital Water: Amount of water measured in one inch of snow.
Precipital Water Chart: On the Precipital Water Chart the top number is the amount of water in hundredths of inches.
The bottom number is the percent of normal for that time of year.

Precipitation: Water in the form of snow, rain. sleet, hail which fall from clouds to Earth.
Precipital Intensity: The rate at which precipitation falls. Light/Moderate/Heavy.
Precipitation Rate: The amount of liquid, water or solid the reaches the ground at a certian amount of time and measured in a raingauge.

"Precipitation Forms" 1.Drizzle: Precipitation composed of fine drops with diameters of less than 0.02 inch (0.5mm). 2.Hail: Small Balls or pieces of falling ice in round or irregular lumps. 3.Ice Pellects: Transparent or translucent round or irregular shapes pellets of ice having a 0.2 inch (5mm)or less. 4.Rain: Falls is the forms of drops larger than 0.02 inch (0.5 mm) 5.Snow: Ice crystals which have six points. 6.Snow Grains: Very small, white, opaque grains of ice.

Pressure Altitude: The standard altitude of a given pressure: Example 500 mb = 18,000 ft.
Pressure Change: The difference between the beginning reading of barometric pressure and the end of a particular time reading.
PRESFR: Pressure Falling Rapidly...When the pressure falls at the rate of 0.06 inch or more per hour.
Pressure Gradient: The closer the isobars the faster the wind speed. Called close/tight or steep pressure gradient. The wider apart the isobars the slower the wind speed. Called: A "Weak" Pressure Gardient.
PRESRR: Pressure Rising Rapidly...When the pressure rises at the rate of 0.06 inch or more per hour.
Pressure Pattern: The rise and fall of pressure during a designated period of time.
Pressure Tendency: The amount of pressure change during a certain period.
Pressure Unsteady: When pressure fluctuates .03 inch of mercury during a certain period of measurement.
Primary Air Polluants: Chloro-Fluro-Carbons: Hair Sprays: Freon: Gasolene: CO2: Sulfur: Nitrogen: Carbon:
PROG: Short for: PROGNOSTIC CHART: A weather Chart (MAP) used in weather forecasting for extended periods: 12HR: 24HR: 36HR: 48HR: 96HR: 30Day: 60DAY: 90DAY:
PROGNOSTIC CHART: A weather Chart (MAP) used in weather forecasting for extended periods: 12HR: 24HR: 36HR: 48HR: 96HR: 30Day: 60DAY: 90DAY:
Pseudo-Adiabatic Lapse Rate: The process of rising air adiabaticly without adding heat or moisture: The dry adiabatice lapse rate of 5 Degs. F, 3 Degs. C., per 1,000 feet.
The moist adiabatic lapse rate of 3 Degs. F., 1.5 Degs. C., per 1,000 feet.
Psychrometer: A weather instrument used to measure relative humidity.
Pyranometer: An instrument used to measure the intensity of solar radiation.

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