ix Climates of the World 145 



and in September the isotherms run west and east once 

 more, and the temperature varies from 52 in Orkney to 

 58 along a line from Pembroke through Bristol and 

 Reading to Lowestoft. The way in which proximity to the 

 sea and exposure to the prevailing winds influences the 

 range of temperature is shown in the following tables : 



Shetland Rothesay Plymouth Inverness Edinburgh London 

 Jan. temp. 39.5 39.5 43.0 37.5 38.0 39.0 



July temp. 53.5 58.0 62.5 58.0 59.5 64.0 



Annual range 14.0 18.5 19.5 20.5 21.5 25.0 



If it were not for the warm south-westerly winds the 

 January temperature would be 7-5 in Shetland, 12-5 at 

 Edinburgh, and 22 at London, and the sea all round the 

 islands would be frozen. 



204. The Rainfall of British Islands has been studied 

 by Mr. G. J. Symons, who publishes an annual volume on 

 British Rainfall. The rainfall is greatest on the west 

 and least on the east coast, warmth always going with 

 wetness (Plate XVII., compare also Plate XVI.) In 

 Ireland, on account of the mountains forming irregular 

 isolated groups, the rainfall is remarkably uniform over the 

 whole island, averaging about forty inches in the year. In 

 Great Britain the low outer Hebrides have a rainfall of 

 about fifty inches, but the high mountains of Skye and the 

 Western Highlands condense more than eighty inches in 

 the year over an area stretching from Skye to Loch Lomond. 

 The mountains of Cumberland and Wales and the high 

 land of Cornwall have also a large rainfall ; but the whole 

 east of Britain has less than forty inches. Most of the 

 district between the H umber and the Thames, the driest 

 part of the British Islands, receives less than twenty-five 

 inches of rain per annum. Contrary to the usual opinion, 

 November is nowhere the rainiest month in the British 

 Islands. The heaviest rainfall in the west and north of 

 Ireland and the west of Scotland takes place in December 

 and January. In England and the east of Scotland it 

 occurs in October, except in the very dry region between 

 the Thames and Humber, where most rain falls in August. 

 In the south of England the least rainy month is March, in 



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