XIX.—The Winds of Ben Nevis

Extract

Noting the direction of the wind is part of the regular routine of observations at the Observatory on the summit of Ben Nevis. Owing to the climatic conditions, especially the frequency of frozen fogs in winter, anemometers are practically useless, but the record is made complete enough for many purposes by the system of hourly observations; at each hour of the day and night the wind, at the time of making the observation, is noted, and the number of entries of each wind direction in the day, month, or year must very nearly represent the relative frequency of such winds for that time. Table I. is a summary giving the number of times each wind is observed in each month of the year on an average of six years (1884–89); February being given in duplicate, that in the body of the table containing 28 days, and that at the foot 29, with the winds divided in the same proportion. The wind is observed to 32 points, but the entries have been reduced to 8 points for this paper by counting all the bys to their adjacent octant, and halving the 8 intermediate points between the octants; thus all N. by E. count as N., all N.E. by N. as N.E., while the N.N.E. entries are halved between N. and N.E., and so on. Perhaps a stricter method of reduction would have been to divide the intermediate points in the ratio of the relative frequency of the adjacent octants, but this would have been considerably more laborious, and of doubtful utility; still it should be borne in mind that the method used tends to smooth out any sudden changes in the frequency of winds of nearly the same direction.