ZIMSEC O Level Geography Notes: Wind direction and speed.
Wind is the movement of air across the earth’s surface due to differences in pressure between two regions. Air moves from high pressure regions to low pressure regions. The differences in pressure can be caused by differential heating of the earth’s surface or by earth and sea breezes.
Two aspects of wind are measured at weather stations:
Wind direction- this is done using a wind wane-the red-tailed instrument in the picture and the information is plotted given in terms of the cardinal points of a compass.
Wind speed- this is done using an cup anemometer and the speed is given in knots or as is increasingly becoming the case in km/hr.