Page:VCH Hertfordshire 1.djvu/77

 CLIMATE is in winter and spring ; autumn and winter, however, have a greater number of wet days than spring and summer. January is on the average the coldest month, and July the warmest. Assuming that the mean temperature of each month occurs about the middle of the month, it would appear that the increase of temperature is most rapid during the month of May, and that the decrease is most rapid during September and October. In two months only, July and August, has the temperature never been below freezing-point (32), and in two months only, December and January, has it never exceeded 62. Tables V., VI., and VII. give particulars of the rainfall for the longest available period under each heading. A day of rain is one on which at least o - oi in. of rain falls, any fall of 0-005 "* to ' OO 9 i n - being considered as o'oi in. TABLE V MEAN AND EXTREME RAINFALL FOR 60 YEARS (1840-99) Mean Rainfall Extreme TV/f .U iviontfis I station 2 stations 7 stations I 2 stations 1 8 stations 20 stations Mean Min. Max. 1 840-49 1850-59 1860-69 1870-79 1880-89 1890-99 1840-99 1854 1852 inches inches inches inches inches inches inches inches inches January . 2'24 2'2O 2'8o 2- 5 8 171 8 1 2'22 1-68 4-85 February . 1-92 I-I9 i-6 7 1-82 1-95 '37 I-6 5 1-14 1-26 March 1-51 1-25 2-04 l-6 7 l- 5 8 82 I-6 5 28 '3 1 April . i'S4 1-88 1-50 2'05 1-91 26 1-69 77 76 May . . 2-08 2-22 2-18 2-13 2'06 66 2'OD 3-58 2-14 June . . 171 2-06 2-39 2'34 1-99 79 2-05 8 5 4-28 July . . 2'12 3-I5 r86 2-64 2-74 2-39 2-48 1-72 3-94 August . 2-30 2-55 2-55 2'6o 1-92 2-75 2-44 r 7 3'93 September 2-45 2'OO 2-47 2-64 2-60 1-96 2-35 55 3-21 October . 3-34 3'22 2'39 2- 5 6 3-i8 3-09 2-96 2-33 4-06 November 2-85 2-23 2-10 2-76 2-84 2-56 2-56 i'37 6-27 December 176 i-55 2-16 2-18 2-26 2*32 2*04 i-53 2-58 Year. . 25-82 25-50 26-II 27-97 26-74 24-78 26-15 17-67 37-59 TABLE VI MEAN NUMBER OF DAYS OF RAIN FOR 30 YEARS (1870-99) Months 1870-79 1880-89 1 890-99 1870-99 Months 1870-79 1880-89 1890-99 1870-99 January. 16 H 16 15 July. . '3 15 '3 14 February. IS '3 12 '3 August. 14 '3 15 H March. H 1 1 14 13 September 13 '3 12 April. . 13 H 12 '3 October. 15 16 16 16 May. . 13 12 12 12 November 16 16 15 16 June. . H II 12 12 December 15 16 16 16 Year. . 171 164 165 167 39
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