REPORT ON METEOROLOGICAL OBSERVATIONS, WISLEY, 1914. 8l 



injury was caused over a very considerable area of the English Midlands. 

 The mean temperature was upon the whole nearly normal ; at Wisley 

 it was one degree below it ; but the month was broken up into periods ; 

 first one of normal warmth, then a rather cold one, followed by another 

 of unusual warmth, and again one of equally unusual cold, thus affording 

 a very good instance of the danger of placing too much confidence 

 in mean values as representing weather conditions over a more or less 

 lengthened period. There was a daily average of more than 6| hours 

 of bright sunshine. On the 7th there was a very sharp thunderstorm 

 at Wisley, and similar storms were experienced in districts covering 

 a wide area ; but there were few strong winds, and no gales of im- 

 portance throughout the month. The Wisley observations give : — 



Mean temperature of the air in shade . . . .52-7° 

 Highest ,, 8o° on the 22nd 



Lowest ,, 31 0 „ 27th 



Lowest „ on the grass . . . . .19° ,, 27th 



Number of nights of ground frost . . . . . . . .14 



At deplh of 

 1 ft. 2 ft. 4 ft. 



Mean temperature of the soil at 9 a.m. . . . 53*1° 5^'5° 51*2° 



Highest „ „ „ „ ... 6o° 56 0 53 0 



Lowest „ „ „ ... 49 0 50 0 49 0 



Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 

 sented by 100), 70 per cent. 



Rain fell on 9 days, to the total depth of 1-07 in. (equivalent to about 5 

 gallons of water to the square yard). Heaviest fall on any day 0*26 in., on the 

 22nd. 



The prevailing winds were north-easterly and south-westerly. 

 The average velocity of the wind was 6 miles an hour. 



There were 210 hours of bright sunshine, equal to 44 per cent, of the greatest 

 possible amount. 



There was one day on which no sunshine was recorded. 



June. — The weather throughout this month was that of a typical 

 midsummer month, generally dry and fine, with an abundance of 

 bright sunshine, a small amount of rain, and two or three thunder- 

 storms. At Wisley there was no storm which could be described as 

 severe ; but over a portion of south-west London and the lower Thames 

 Valley there was one, on the 14th, of quite unusual severity, that caused 

 some loss of life, a considerable amount of structural damage, and 

 heavy rain over a wide area, but amounting locally to a veritable 

 deluge. It is of interest to record here that most of the loss of life 

 was amongst those who had sought shelter beneath trees. But 

 generally the total rainfall for the month was strikingly small ; at 

 Wisley it was only one-third of the average, and over a considerable 

 area of southern England it did not exceed one-sixth of the normal 

 fall. Sunshine, on the other hand, was very abundant, more than half 

 of the possible amount being registered over a large part of the 

 kingdom. At Wisley there was not a single day in the course of which 

 the sun failed to leave some record, and the average daily amount was 

 more than eight and a half hours. The mean temperature, also, was 

 above the average over the greater part of the kingdom, and the close 

 of the month was marked by some exceptionally warm days ; but once 

 or twice during the month the terrestrial radiation during the night 



VOL. XU. G 



