40 Climate 



climate, but the average annual value for Cambridge is much the same, 

 and the range of monthly means, although double that for Valentia, shows 

 both a higher maximum and a lower minimum: but even this minimum 

 is high. Berlin, on the other hand, shows a much wider range, with a 

 maximum in December and a ininimum in May-June. The depressing, 

 enervating effect of the Cambridge climate is doubtless due to its high 

 humidity, and even Indians complain of the heat during a hot spell in the 

 summer. It seems likely, however, that the high humidity is due in part 

 to local causes, but chiefly to the " continentality " of the neighbourhood. 

 This arises from the large diurnal range of temperature with values at 

 night and early morning falhng to dew point. The result is that the readings 

 at 9 h. and 21 h. tend to be liigh, particularly in later autumn and winter. 



SUNSHINE AND CLOUDINESS 



The variations for bright sunsliine (Table 7; Fig. 15) show relatively small 

 differences from October to April for Valentia, Cambridge, and Berlin. 

 From May to September, however, the differences are appreciable; 

 Cambridge then occupies an intermediate position. Although the total 

 number of hours of sunshine is less than that enjoyed by parts of the south 

 coast, yet the Cambridge neighbourhood is sunny compared with the 

 west. 



The data for cloudiness (Table 8) show the nearer approach of Cambridge 

 to Berhn during April to September : from September to April, Cambridge 

 has the least cloudiness of all these places and also the lowest average for 

 the year. 



The preceding data show that while the climate of Cambridge is not 

 continental, it has a number of continental features, the fuller expression 

 of which is checked by a high humidity. 



GENERAL CONSIDERATIONS 



The weather varies much from year to year and from place to place. 

 Even minor differences in topography are significant to plant life and to 

 man : a few feet may raise them above an accumulation of cold air or of 

 fog. But the major variations are determined by major causes — namely, 

 the position of Cambridge in relation to the centres of low- and high- 

 pressure systems in north-western Europe. In general, the air moves from 

 south-west to north-east, due to the frequency of cyclones centred (i) to 

 the north-west of the country, or (2) directly over the British Isles or over 

 the Channel; the former bring "orographic" rain to the west, the latter 

 "cyclonic" rain to all parts of the country. The rainfall of Cambridge is 



