Directional Convergence Forced by the Terrain

Higher elevations on both sides of the narrowing tip of Lake Superior force broad low level convergence as winds blow toward the head of the lake from an east-northeast direction. When winds are more from the east, the hill along the north shore of Lake Superior deflects some of the air so that the air flows parallel to the hill. The difference between the direction of the deflected air and the direction of air approaching from the east results in directional convergence of the two air flows. Directional convergence is one of several mechanisms that contributes to the overall convergence that occurs at the head of Lake Superior.