A line connecting or marking places upon the surface of the earth where height of the barometer reduced to sea level is the same either at a given time, or for a certain period (mean height), as for a year; an isopiestic line
A line drawn on a map or chart connecting places of equal or constant pressure In meteorology, it most often refers to a line drawn through all points of equal atmospheric pressure along a given reference surface, such as a constant height surface (notably mean-sea-level on surface charts); the vertical plane of a synoptic cross section, or a map of the air unaffected by surface heating or cooling The pattern of isobars has always been a main feature of surface chart analysis Until recently it was standard procedure to draw isobars at 3-millibar intervals However, the advent of constant pressure charts for upper-air analysis has brought about the use of 4-millibar intervals to simplify the conversion from surface isobars to 1,000-millibar contour lines
Is a process taking place under constant pressure To change the volume from state 1 to state 2, heat must be removed The temperature change is proportional to the change in specific volume (060)