highlights the counterclockwise rotation in the ridge, and the clockwise
rotation in the trough. Areas of upper divergence are normally found on the
backside of a ridge, and on the forward side of a trough, while upper
convergence is normally found on the backside of a trough and on the forward
side of a ridge. However, this is a subjective representation of where the
maximum areas of divergence/convergence are located. Depending on the vertical structure of the
ridge/trough, the best divergence or convergence could be closer to the axis.