Use the “Quick Search” box to locate your required term and/or definition. The following “Search conditions” can be used to refine your search: “Contains”, “Begins with”, “Ends with”, “Equals”, “Does not contain” or “Does not equal.”
Eng ID Term Definition
4021
preferred channel mark
A distinctive lateral mark used to indicate both the point at which a channel divides and the channel that has been designated as preferred ... more
A distinctive lateral mark used to indicate both the point at which a channel divides and the channel that has been designated as preferred channel.
4022
preferred datum
A geodetic datum selected as a base for consolidation of local independent datums within a geographical area. Also called major datum.
4023
preliminary survey
See SURVEY: RECONNAISSANCE.
4024
press proof
A lithographed impression taken from among the first copies run on the press and used for checking purposes. Also called press pull.
4025
pressure: atmospheric
Pressure (force per unit area) exerted by the ATMO­SPHERE, on any surface, by virtue of its WEIGHT: it is numerically equal to the WEIGHT o... more
Pressure (force per unit area) exerted by the ATMO­SPHERE, on any surface, by virtue of its WEIGHT: it is numerically equal to the WEIGHT of a vertical column of air above the surface of unit base area, extending to the outer limit of the ATMOS­PHERE.
4026
pressure: barometric
ATMOSPHERIC PRESSURE as indicated by a BAROMETER.
4027
pressure: hydrostatic
The pressure at a given DEPTH due to the WEIGHT of the water column above that DEPTH.
4028
pressure: sound
The instan­taneous pressure at a point in a medium in the presence of a SOUND WAVE, minus the static pressure at that point.
4029
pressure-altitude
An ATMOSPHERIC PRESSURE ex­pressed in terms of ALTITUDE which corresponds to that pres­sure in the STANDARD ATMOSPHERE.
4030
pressure gauge
See GAUGE.
4031
pressure gradient
Vector, perpendicular to the isoba­ric line or surface, directed towards low pressure and of intensity equal to the rate of variation of th... more
Vector, perpendicular to the isoba­ric line or surface, directed towards low pressure and of intensity equal to the rate of variation of the pressure with distance. Also called barometric gradi­ent.
4032
pressure hydrophone
A HYDROPHONE in which the elec­tric OUTPUT substantially corresponds to the instantaneous SOUND PRESSURE of the impressed SOUND WAVE.
4033
pressure ice
A general term for FLOATING ICE which has been squeezed together and in places forced up­wards, when it can also be described as RAFTED ICE... more
A general term for FLOATING ICE which has been squeezed together and in places forced up­wards, when it can also be described as RAFTED ICE, HUMMOCKED ICE, PRESSURE RIDGE, TENTED ICE.
4034
pressure plate
In PHOTOG­RAPHY, a flat plate (usually of metal but frequently of glass or other substance) which, by means of mechanical force, presses fi... more
In PHOTOG­RAPHY, a flat plate (usually of metal but frequently of glass or other substance) which, by means of mechanical force, presses film into contact with the focal-plane plate of a CAMERA.
4035
pressure ridge
A ridge or wall of HUMMOCKED ICE where one FLOE has been pressed against another.
4036
pressure wave
A short-period oscillation of pressure such as that associated with the propaga­tion of SOUND through the ATMOSPHERE; a type of LONGITUDINA... more
A short-period oscillation of pressure such as that associated with the propaga­tion of SOUND through the ATMOSPHERE; a type of LONGITUDINAL WAVE.
4037
Price-Gurley current meter
A battery powered electro­me­chanical CURRENT METER which measures current speed only.
4038
pricker
A pointed tool used instead of a pencil for laying off finer and more accurate lines on a PLOTTING SHEET.
4039
primary circle
See PRIMARY GREAT CIRCLE.
4040
primary great circle
A GREAT CIRCLE used as the origin of measurement of a COORDINATE; particularly such a circle 90° from the POLES of a system of SPHE­RICAL ... more
A GREAT CIRCLE used as the origin of measurement of a COORDINATE; particularly such a circle 90° from the POLES of a system of SPHE­RICAL COORDINATES, as the EQUATOR. Also called primary cir­cle, fundamental circle.