Atmospheric PressureThe pressure exerted by the earth's atmosphere at any given point, determined by taking the product of the gravitational acceleration at the point and the mass of the unit area column of air above the point.Barometric PressureThe pressure of the atmosphere as indicated by a barometer.Cone of DepressionIn hydrologic terms, the depression, roughly conical in shape, produced in a water table, or other piezometric surface, by the extraction of water from a well at a given rate. The volume of the cone will vary with the rate of withdrawal of water. Also called the Cone of Influence. Constant Pressure ChartAlternate term for Isobaric Chart; a weather map representing conditions on a surface of equal atmospheric pressure. For example, a 500 mb chart will display conditions at the level of the atmosphere at which the atmospheric pressure is 500 mb. The height above sea level at which the pressure is that particular value may vary from one location to another at any given time, and also varies with time at any one location, so it does not represent a surface of constant altitude/height (i.e., the 500 mb level may be at a different height above sea level over Dallas than over New York at a given time, and may also be at a different height over Dallas from one day to the next).DepressionA region of low atmospheric pressure that is usually accompanied by low clouds and precipitation. The term is also sometimes used as a reference to a Tropical Depression.Depression StorageIn hydrologic terms, the volume of water contained in natural depressions in the land surface, such as puddles.Dew Point DepressionThe difference in degrees between the air temperature and the dew point.LOPRESlow pressureLow Pressure SystemAn area of a relative pressure minimum that has converging winds and rotates in the same direction as the earth. This is counterclockwise in the Northern
Hemisphere and clockwise in the Southern Hemisphere. Also known as an cyclone, it is the opposite of an area of high pressure, or a anticyclone. PRESPressurePrescribed FireA management ignited or natural wildland fire that burns under specified conditions where the fire is confined to a predetermined area and produces the fire behavior and fire characteristics required to attain planned fire treatment and resource management objectives.Present MovementThe best estimate of the movement of the center of a tropical cyclone at a given time and given position. This estimate does not reflect the short-period, small scale oscillations of the cyclone center.Present WeatherThe type of weather observed at the reporting time. These conditions may include types and intensity of precipitation such as light rain or heavy snow, as well as the condition of the air environment such as foggy, hazy or blowing dust.PressureThe exertion of force upon a surface by a fluid (e.g., the atmosphere) in contact with it.Pressure AltimeterAn aneroid barometer calibrated to indicate altitude in feet instead of units of pressure. It is read accurately only in a standard atmosphere and when the correct altimeter setting is used.Pressure AltitudeThe altitude in standard atmosphere at which a given pressure will be observed. It is the indicated altitude of a pressure altimeter at an altitude setting of 29.92 inches of mercury, and is therefore the indicated altitude above the 29.92 constant pressure surface.Pressure ChangeThe net difference between the barometric pressure at the beginning and ending of a specified interval of time, usually the three hour period preceding an observation.Pressure CharacteristicThe pattern of the pressure change during the specified period of time, usually the three hour period preceding an observation. This is recorded in three categories: falling, rising, or steady.Pressure CoupletIt is an area where you have a high pressure area located adjacent to a low pressure area.Pressure Falling RapidlyA decrease in station pressure at a rate of 0.06 inch of mercury or more
per hour which totals 0.02 inch or more.Pressure GageA device for registering the pressure of solids, liquids, or gases. It may be graduated to register pressure in any units desired.Pressure GradientThe amount of pressure change occurring over a given distance.Pressure Gradient ForceA three-dimensional force vector operating in the atmosphere that accelerates air parcels away from regions of high pressure and toward regions of low pressure in response to an air pressure gradient. Usually resolved into vertical and horizontal components.Pressure HeadEnergy contained by fluid because of its pressure, usually expressed in feet of fluid (foot pounds per pound).Pressure IceFloating sea, river, or lake ice that has been deformed, altered, or forced upward in pressure ridges by the lateral stresses of any combination of wind, water currents, tides, waves, and surf.Pressure Induced WaveA rare type of wave that does not develop from wind or seismic activity. Instead, these waves develop as a pressure perturbation moves over the water surface. The water surface adjusts to account for the atmospheric pressure change. As atmospheric pressure decreases, the force exerted upward by the water increases, creating a pressure induced wave. Pressure JumpA sudden, sharp increase in atmospheric pressure, typically occurring along an active front and preceding a storm.Pressure Rising RapidlyAn increase in station pressure at a rate of 0.06 inch of mercury or more per hour which totals 0.02 inch or more.Pressure TendencyThe character and amount of atmospheric pressure change during a specified period of time, usually 3-hour period preceding an observation.Pressure UnsteadyA pressure that fluctuates by 0.03 inch of mercury or more from the mean pressure during the period of measurement.Pressure-driven ChannelingChanneling of wind in a valley by synoptic-scale pressure gradients superimposed along the valley's axis. Compare forced channeling.Saturation Vapor PressureThe vapor pressure of a system, at a given temperature, wherein the vapor of a substance is in equilibrium with a plane surface of that substance's pure liquid or solid phase.Sea Level PressureThe sea level pressure is the atmospheric pressure at sea level at a given location. When observed at a reporting station that is not at sea level (nearly all stations), it is a correction of the station pressure to sea level. This correction takes into account the standard variation of pressure with height and the influence of temperature variations with height on the pressure. The temperature used in the sea level correction is a twelve hour mean, eliminating diurnal effects. Once calculated, horizontal variations of sea level pressure may be compared for location of high and low pressure areas and fronts.Station PressureThe absolute air pressure at a given reporting station. The air pressure is directly proportional to the combined weight of all air in the atmosphere located in a column directly above the reporting site. Consequently, the station pressure may vary tremendously from one location to another in mountainous regions due to the strong variation of atmospheric pressure with height. Vertical variations of pressure range up to 150 mb per mile whereas horizontal variations are usually less than .1 mb per mile.Subtropical DepressionA subtropical cyclone in which the maximum 1-minute sustained surface wind is 33 knots (38 mph) or less. Tropical DepressionA tropical cyclone in which the maximum 1-minute sustained surface wind is 33 knots (38 mph) or less.Vapor PressureThe partial pressure of water vapor in an air-water system.
You can either type in the word you are looking for in the box below or browse by letter.
Browse by letter:# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z