Graphical Determination of the Geostrophic Wind Over a Point or Small Area
Assuming straight, parallel, and equally-spaced contour heights or isobars over a small area, the total pressure-gradient force (and the geostrophic wind) may be determined graphically using the contour-height or sea-level pressure differences between 3 stations around the area. The method is objective and eliminates personal discrepancies in scaling geostrophic wind from pressure or contour-height analyses.