METEOROLOGICAL OBSERVATIONS AT WISLEY IN 190-3. 177 



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



represented by 100; 92 



Rain fell on 20 days to the total depth of 3-17 ins. 



(Equivalent to about 14f gallons of water per square yard.) 



Heaviest fall on any day 0*57 in. on the 10th 



he winds came with nearly equal frequency from all points. 

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



There were 65 hours of bright sunshine, equal to 25 per cent, of the total possible 

 amount ; there was no sunshine registered on nearly half the days of the month. 



December— The month was a quiet one as regards wind, unusually 

 dry, and at the same time abnormally mild. There was much fog and 

 thick mist in the earlier days of the month, but the latter part was clear 

 and bright. 



The most prevalent winds blew from between south and west, and 

 were for the most part moderate in force. Temperature was considerably 

 above the average almost everywhere, as much as 5° in some western and 

 northern districts. At the close of the first week the thermometer rose 

 to 57° and 58° at many places, the lowest readings being as a rule 

 between 20° and 25°, so that the range of temperature was much less 

 than is usual in December. Rainfall was decidedly small, and heavy 

 daily falls very few. In many parts of the country the month's pre- 

 cipitation was 2 and 3 inches less than the usual amount, and indeed 

 in some parts, chiefly in the north-east of England, the total amounts 

 were less than a quarter of an inch. Sunshine was somewhat irregularly 

 distributed, some places having rather more and others less than the 

 average, but the recorded percentages of the greatest possible amount 

 were nowhere large. 



Observations made at ^Wisley : 



Mean temperature of the air in shade 40°. 4 



Highest „ „ „ 56°.7 on the 7th 



Lowest „ „ „ 24°.2 „ 11th 



Lowest ,, on the grass 21°.9 „ 11th 



At l ft. At 2 ft. At 4 ft. 

 deep. deep. deep. 



Mean temperature of the soil at 9 a.m 41°.3 43°.l 44°.9 



Highest „ „ * ' „ 46°.4 45°.6 45°.9 



Lowest „ „ „ 38°.2 41°.8 44°.l 



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



represented by 100) 92 



Rain fell on 15 days to the total depth of 0'57 in. 



(Equivalent to rather more than 2§ gallons of water per square yard.) 



Heaviest fall on any day 0-10 in. on the 5th, 8th, and 27th days 



The prevailing winds were south-westerly. 



The average velocity of the wind was 5 miles per hour. 



There were 32 hours of bright sunshine, equal to 13 per cent, of the total possible 

 amount. There were as many as 19 sunless days. 



The accompanying diagrams show in a graphic form the chief features 

 of the preceding tables. 



Fig. 37 shows first the departure of the mean temperature of each 

 month from the average. It will be seen that the temperature did not 

 fall below the average until August, which was the first of four consecu- 

 tive cold months, the coldest being October. This spell of cold weather 



N 



