Abstract
Special emphasis is given to the fact that there exists a very close relation between cyclo- and anticyclo-genesis and the form of mountain obstacles., i.e., the properties expressed by ∂2z/∂x∂y (the convergence and divergence of the mountain contours z0 = z0 (x,y) = constant) and Δz0 = ∂2z0/∂x2 + ∂2z0/∂y2 (a measure of terrain concavity, Δz0 > 0, and convexity, Δz0 < 0). The physical basis of this relationship involves the vertical motions which arise due to the form of the mountain obstacles. If this relation is not considered in the numerical model for predicting the pressure field the results will be influenced by a significant systematic error. Examples are given.
