دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

abbr: Instrument Society of America. isobar n: a line drawn on a weather map connecting points of equal atmospheric pressure.

Instrument Society of America.

n: 1. a scale of pressure differences in which there is a uniform variation of pressure from point to point. For example, the pressure gradient of a col- umn of water is about 0.433 pounds per square inch per foot (9.794 kilopascals per metre) of vertical elevation. The normal pressure gradient in a formation is equiva- lent to the pressure exerted at any given depth by a column of 10 percent salt water extending from that depth to the surface (0.465 pounds per square inch per foot, or 10.518 kilopascals permebe). 2. the change (along a horizontal distance) in atmospheric pressure. Isobars drawn on weather maps display the pressure gradient.

n: the variation of pressure with depth.commonly used under hydrostatic conditions(e.g. a hydrostatic column of salt water has a pressure gradient of 0.465 psi/ft).

change in pressure with depth.

n: see weather map.

n: a chart that indicates atmospheric conditions and circulation over an area at a given time. Also called surface chart.