METEOROLOGICAL OBSERVATIONS AT AVISLEY IN 1907. 519 



The prevailing winds were westerly. 



The average velocity of the wind was 7^ miles per hour. 



There were 1994 hours of bright sunshine, equal to. 55 per cent, of the greatest 

 possible amount. There were only 2 days on which no sunshine was recorded. 



April. — The weather of this month was very unlike that of March, 

 the exceptionally brilliant character of which now became changed into 

 an unusually wet, cold, and ungenial period. Over the northern half of 

 the kingdom, however, the rainfall did not reach the average amount, but 

 elsewhere the average was exceeded. Thunderstorms occurred in several 

 parts of the kingdom and occasionally did considerable damage, especially 

 in those instances in which they were accompanied by heavy falls of 

 hail. In one which occurred on the 7th, in Northamptonshire, the hail 

 accumulated in drifts to a depth of from four to five inches. On the 

 night of the 6th-7th, there was also over the south-eastern counties a 

 very heavy fall of snow, which, on the North Downs, amounted to a 

 depth of six inches. There was, however, an absence of very strong 

 winds, but fog was more prevalent than usual, especially in the west and 

 south-west. On the whole the weather was favourable to vegetation, the 

 rain doing much good notwithstanding the cold and the somewhat scanty 

 amount of sunshine. 



Observations made at Wisley : 



Mean temperature of the air in shade 46 0, 8 



Highest „ „ „ 71°'5 on the 24th 



Lowest „ „ „ 29°-4 „ 19th 



Lowest „ on the grass 25°*3 „ 1st 



At I ft. At 2 ft. At 4 ft. 

 deep. deep. deep. 



Mean temperature of the soil at 9 a.m 47°-0 47°'7 46°-5 



Highest „ „ „ 52°-4 50°-8 48°-l 



Lowest „ „ „ 45°1 46°-2 44°-8 



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



represented by 100) 79% 



Rain fell on 19 days to the total depth of 3*55 in. 



(Equivalent to about 16§ gallons of water per square yard.) 

 Heaviest fall on any day ... ... ... ... ... ... 0*72 in. on the 6th 



The winds were variable in direction. 



The average velocity of the wind was 6^ miles per hour. 



There were 145-7 hours of bright sunshine, equal to 35 per cent, of the greatest 

 possible amount. There were only 4 days on which no sunshine was recorded, 

 and on two occasions the amount for the day reached 11 hours. 



May. — The weather of this month was very variable in character, with 

 considerable range of temperature between the maximum in the day and 

 the minimum at night ; it was often cold, dull, and rainy, with occasional 

 hail, sleet or snow, and not infrequently thunderstorms, which in some 

 instances were very severe. The fall of rain was generally in excess, and 

 the amount of sunshine below the average, the total duration of the latter 

 being in many instances less than that recorded in April ; the temperature 

 was also in most parts of the kingdom below the average. The sudden 

 changes of temperature were not good for the fruit trees, and the cold 

 winds checked the growth of pastures and of plant life generally, but the 

 rains were beneficial, and at the close of the month the general outlook 

 as regards crops was good. 



