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OOH82 . Anemometers developed specifically to measure high wind velocities commonly are not suitable at low velocities. Among wind vanes, one that is heavy may oscillate less than one that is light and so may mask short- period changes in direction, or may over-swing on sudden changes. A vane that is large and that has a relatively long tail tends to smooth out many whirlS and eddies to which a short vane would respond. . Mechanical failure during periods of low temperature may involve complete stoppage by accumulated ice or snow, or substantial under-registry owing to cQngealed lubricant in bearings. An instrument impropel'lyeleaned and oiled may under-register at any time. As will be obvious, erroneous records so caused are all but impossible to identify and adjust. Use of data on wind Wind records are useful for a wide range of purposes, including (1) the selection of sites for airports, industrial plants, wind-power generators~ and meteorologic stations; (2) estimating wind loads on buildings,'television towers, or other struetures;(3) study of the distributiQn and dilution of dust, pollen, pollutants, and cloud-seeding nuclei; (4) determining wind effect on the formation and movement of ice in streams;and lakes; also on wave action and its relation to shore erosion and to loa~ing and movement of ships; and (~) weather forecasting, both in general an~ in particular regard to forest~fire warning and fighting, frost warning, and air-borne commerce. Wind ts a principal variable in the investigation, forecastipg or calculation of evaporation. Its speed, direction, eddy structure and variation with height influence the rate at which the vapor molecules are removed from the immediate vicinity of the liquid surface. Wind ts responsible for drifting and strongly effects the deposit of snow aroun~ and on obstacles such as buildings, fences, bridges, and roofs. It is a releVant parameter in the estimation and study of snoW-melt rates and amounts. . VI.4 Wind is known to have substantial influence on the catch of precipitation gages, the catch diminishing as wind speed increases. This effect is I1I\ldh more marke<;l with snow than with rain. It can be countered by shielding the gage orifice and by locating gages at sites protected from the wind. The orography of a region has a pronounced effect on wind flow, whiqh in turn strongly itlfluences the rate and distribution of precipitation. These orog:i'aphic influences can result in more preCipitation on windward slopes and'on steep slopes than on lee slopes and gentle slopes.