I'm studying for an exam and I'm having a problem understanding a picture from book "An Introduction to Dynamic Meteorology" by James R. Holton (fig 6.6 in version 2004).
I'm not sure if I correctly understood what are a "ridge" and a "trough" on that picture. Are those lines group of points that show min/max of geopotential at each height in an isobaric coordinate system?
For example, if I draw a straight line parallel to an X axis at some height (for example 500 hPa) would points of intersections with "ridge" and "trough" lines give me points of max/min values of geopotential at that height?
