climate 3 5 



column); (b) an increasing range of temperature in any month; and 

 (c) increasing differences between the summer maxima and between the 

 winter minima. The values for the winter maxima and summer minima 

 approximate. But Cambridge is peculiar in having the liighcst winter 

 maxima and the lowest summer minima of all three stations. 



These low summer minima around Cambridge are particularly im- 

 portant, for they indicate the frequency of frosts (Table 3). Extreme minima 

 below 32° F. are recorded for Valentia from December to March; for 

 BerUn from October to April; but for Cambridge from October to May. 

 Indeed, at Cambridge serious frosts quite often occur m the begiiming of 

 June and the only month really free from frost is July. Winter frosts 

 also are severe, and the damage they do is likely to be increased because 

 snow affords an efficient protection only on a few days of the year: in an 

 average year snow lies in the morning for 12 days only. Skating is enjoyed 

 ever)' other year, and the last occasion when the Cam was converted into 

 a liighway was February 1929. 



RAINFALL 



Both in the amount of rainfall and in its distribution throughout the year, 

 Cambridge again shows a distinct approach to the continental type of 

 climate (Tables 4 and 5; Fig. 13). 



Like the continental stations, Cambridge has a low yearly total: Valentia 

 has over twice as much rain as Cambridge, and its lowest monthly value 

 is much greater than the highest at Cambridge. 



The total for Cambridge itself is a fair sample of the annual rainfall of 

 the Cotmty: the average for twenty-eight stations within the Coimty, at 

 altitudes varying from 6 ft. o.d. to 286 ft. o.d., is 22-28 in. The range is 

 narrow — from 20-6 in. at Upwell to 24-7 in. at Conington. To the 

 west, m Huntingdon and Bedford, and to the east, in Suffolk, the rainfall 

 is slightly higher. 



The distribution of the rainfall throughout the year is particularly 

 interesting. The typical oceanic chmate shows a summer minimum and a 

 winter maximum, the typical continental the reverse. Throughout the 

 greater part of the British Isles, the rainfall of the winter half of the year is 

 greater than that of the summer half, a feature which the country shares 

 with a strip of Atlantic seaboard of the continent. But a relatively small 

 area in east-central England, including Cambridge, shows the reverse, 

 namely, a greater fall during the summer half than during the winter half 

 year. This is a continental feature that is further emphasised by a con- 

 sideration of the details. A glance at the graph for Orenburg shows the 

 typical feature of a continental climate, namely, the high peak in late 



3-2 



