THE CLIMATE OF NOTTINGHAMSHIRE 59 



fluence must not be pressed too far regarding temperature, for in winter, 

 west and south-west winds often blow, as elsewhere, with characteristic 

 mildness and raise the temperature several degrees. Prolonged cold 

 spells, on the other hand, are not uncommon owing to the establishment 

 of anticyclonic conditions over the continent resulting in the drift of 

 easterly winds across the North Sea. 



Pressure and Winds 



In the absence of data for local stations the following table giving the 

 mean monthly barometric pressure for Derby, situated only 16 miles 

 from Nottingham, should be of general interest, though of little practical 

 value in making a detailed study. Day-to-day changes are of course 

 vastly more important. 



Mean Monthly Atmospheric Pressure at Derby in Inches 



Jan. Feb. Mar. April Mav Jiuie 



29-900 29-917 29-860 29932 29969 29 955 



July Aug. Sep. Oct. Nov. Dec. 



29-932 29-910 29-904 29-856 29-892 29-932 



Weather conditions in Nottinghamshire, as in all parts of the British 

 Isles, are largely governed by the prevalence of westerly winds throughout 

 the year. The following table shows the average number of days in each 

 month experiencing winds with components from the four cardinal points 

 of the compass at Nottingham. 



Wind .Tan. Feb. Mar. Apr. Mav June July Aug. Sep Oct. Nov. Dee. Year 

 N. 66 899'8 7"588 7 586 

 p]. 4 5 4 6 6 5 5 3 5 5 4 3 55 

 S. 54444 4454545 52 

 W. 17 14 15 12 12 13 15 17 14 13 14 16 172 



Computed from daily readings publisiied in the annual reports on the 

 meteorology of Nottingham, for the period of tiiirty-tive years, 1891-1925. 



Winds with a westerly component thus blow during 172 days, i.e. 

 nearly half the total number of days in the year. They are felt on at 

 least 12 days in every month and are most frequent in January and 

 August and least in April and May. Similar observations made at Hod- 

 sock Priory over a period of 30 years (1876-1905) show that west and 

 south-west winds together prevail there for almost one-third of the days 

 in the year. 



Northerly winds blow during nearly one-quarter of the days of the 

 year and predominate in April and May when there is a weakening of 

 the westerlies. Easterly winds are commonest in April and May, though 

 at Hodsock they are most frequent in March. Southerly winds, though 

 less frequent than those from other quarters, blow during a uniform 

 number of days each month. The table deals only with the average 

 monthly occurrence of the various winds and conveys no idea of their 

 strength or of the length of time they prevailed. True calm days, i.e. 

 days on which no movement of the air is recorded at the time of obser- 

 vation, are seldom experienced and these have been disregarded in com- 



