Gustiness Under Various Weather Conditions*

Abstract

Synopsis Records of gustiness or rapid variations of velocity, usually obtained during gales, are important in studies of destructive effects of high winds, and from these data the relation of variations of high frequency to high mean velocities during long periods of time has been determined with fair accuracy. Gales, however, accompany but one or two kinds of condition, and a desirable supplementary comparison of gustiness with other phenomena of the atmosphere—storms, cloudiness, diurnal changes of pressure and temperature, etc.—has been undertaken at Blue Hill Observatory under the very favorable circumstances of an unusual range of velocity, ideal exposure for instruments, and wide-scale continuous records of all elements. Gustiness, by a highly-sensitive rotation anemometer, is recorded on paper moving 60 mm a minute during periods of about 20 minutes regularly at 8 A.M., 2 P.M., and sunset, and at other hours during unusual conditions. The rotor can measure five changes of velocity in one second and the time-scale of the recorder can be expanded to 40 mm a second when details are to be studied. The records obtained so far confirm earlier data of the connection between variable velocities and the more conspicuous changes of condition of the atmosphere, the range of velocity and frequency of gusts being higher on days with strong convection than during other periods when the sky is overcast and the vertical component of the wind is small. Further study of records will be necessary to evaluate relationships not so obvious but possibly of greater importance.