Water-spouts and Tornadoes

Abstract

WHEN at Frinton recently I was interested to notice a series of whirls like water spouts on a small scale forming on the beach. The smooth, sandy beach at Frinton is protected by a series of low wooden groynes consisting of planks supported at intervals by posts sonie nine inches square driven into the sand. The planks rise to about a foot above the sand and the posts project soméwhat more, as shown in the sketch (Fig. 1). The wind was blowing up the beach slantwise to the groynes in the direction of the arrow, and inthe corner between each post and groyne a perfect little tornado or water-spout was formed. The breaking waves were throwing up foam which was trapped in the shallow pools behind the posts, and this foam was whirled round and lifted into the air by the eddy, the foam thrown by each successive wave being quickly carried away over the groyne. Thus far the phenomena described scarcely call for comment, as the wind blowing round the post would, naturally, cause an eddy in the corner, but the remarkable fact was that the eddies were of such violence that not only foam but drops of water were lifted and, at times, a raised cone of water was visible in the centre which appeared to be at least 1/4-inch high. Where did the suction come from?