36 SCIENTIFIC SURVEY OF BLACKPOOL AND DISTRICT 



is only 35.67, compared with the postulated 40 inches as the average general 

 rainfall of the British Isles. Eastwards this level is not reached until the land 

 rises up the slopes of Bowland. 



Rainfall is least from February to June., with a minimum in April ; it rises 

 in July and in August reaches a level twice that of April ; it falls in September, 

 but rises again in October as high or higher than in August ; it is less in 

 November and in December and January, and is at a level intermediate 

 between October and September. The transitions between the relatively 

 dry season of February- June and the relatively wet season of July-January 

 (with a break in September) are graded and without discontinuities, in the 

 sense in which the term is used by Crowe and Matthews (see footnote). The 

 range of variation or dispersion within each month is indicated by the quartiles 

 given in the statistical tables. 2 It will be seen that the lower quartiles of 

 July and September are as low as the lower quartiles of the months — February 

 to June inclusive — of the relatively dry season, but that their upper quartiles 

 are much higher than the upper quartiles of March-June. In other words, 

 one quarter of the rainfalls of September are as low as one quarter of the rain- 

 falls of April, but while there are very wet Septembers (e.g., September, 1935), 

 the rainfall of April is never very high. July and September are clearly 

 intermediate between the relatively dry and relatively wet seasons, sometimes 

 belonging to the one and sometimes to the other. But the lower quartile of 

 August is the highest of all and, ironically in this holiday month, the expectation 

 of rain is the greatest. 



The wide range between the sunshine maximum of June and minimum 

 of December implies that the influence of solar control is accentuated by the 

 contrast of anticyclonic weather and clear skies in the former, and of cyclonic 

 weather and cloudy skies in the latter. On the Lancashire coast sunshine is 

 at a much higher level than in the inland districts nearer to the foot of the 

 Pennines, whether they be industrial or not. In the industrial districts 

 domestic and factory smoke still further obscures the sky, so that sunshine is 

 often only two-thirds of what it is on the coast. The discrepancy is greatest 

 in December and January when the industrial towns receive on the average 

 less than one hours sunshine daily. In summer the extra sunshine of the 

 coast is a contributory meteorological factor in the temporary seaward migration 

 of population. 



The land and sea breeze circulation considerably reduces summer heat 

 along the Fylde coast. It is developed only during calm, anticyclonic weather. 

 The sea breeze develops during the forenoon from the south-west, gradually 

 freshens and veers through west to north-west in the afternoon. It dies down 

 about sunset and a light land breeze from the east soon develops and blows 

 until daybreak, after which it gradually veers through south-east and south 

 to emerge again as a sea breeze in the forenoon. The effect of the sea breeze 

 is usually pleasant, for the sunshine remains, though the air is cooler, but 

 occasionally a distinctly unpleasant ' sea-fog,' half-saturated with vapour drawn 

 up from the sea by the hot sun, spreads over the coast. This circulation 



2 For a discussion of the value of the median and quartiles in rainfall interpretation see papers 

 by P. R. Crowe and H. A. Matthews in the Scottish Geographical Magazine, March, 1933, and 

 March, 1936, respectively. 



