Wind sock. The wind sock is used at airfields to give a quick and simple indication of the wind vector (speed and direction) at ground level. It is simply a hollow cone of material, fixed loosely to a pole. The angle between the wind sock and the pole gives an indication of the wind strength; this wind sock shows a wind speed of 5-10 knots (9-18 km/h). This is of particular use at smaller airfields where little specialist meteorlogical information is available. Other uses include industrial complexes or effluent treatment plants which might emit noxious or unpleasant fumes; emission is curtailed when the wind would carry smells into populated areas.