RELATION OF RAINFALL IN 1950 TO THE AVERAGE OF 1881-1915. RAINFALL IN SCALE OF TINTS 1950 PERCENT OF AVERAGE 0 50 100 AIR MINISTRY, METEOROLOGICAL OFFICE. The area coloured Red had rainfall below the average, that coloured Blue had rainfall above the average. British Rainfall, 1950 } [ Frontispiece 4756-4402-M.3171-750-IO/5Z.(M.F P.) M.O. 560 AIR MINISTRY METEOROLOGICAL OFFICE BRITISH RAINFALL 1950 THE NINETIETH ANNUAL VOLUME OF THE BRITISH RAINFALL ORGANIZATION Report on the DISTRIBUTION OF RAIN IN SPACE AND TIME OVER GREAT BRITAIN AND NORTHERN IRELAND DURING THE YEAR 1950 AS RECORDED BY ABOUT 5,000 OBSERVERS WITH MAPS 60549 LONDON : HER MAJESTY'S STATIONERY OFFICE 1952 CROWN COPYRIGHT RESERVED PUBLISHED BY HER MAJESTY'S STATIONERY OFFICE To be purchased from York House, Kingsway, LONDON, w.c.2 423 Oxford Street, LONDON, w.l P.O. Box 569, LONDON, s.E.l 13a Castle Street, EDINBURGH, 2 1 St. Andrew's Crescent, CARDIFF 39 King Street, MANCHESTER, 2 Tower Lane, BRISTOL, 1 2 Edmund Street, BIRMINGHAM, 3 80 Chichester Street, BELFAST or from any Bookseller 1952 Price £1 5s. Off. net S.O, Code No. 40 10-0-50* CONTENTS PAGE PAGE PART I PART ffl 1. THE WORK OF THE BRITISH RAINFALL PAPERS ON RAINFALL IN British Rainfall ORGANIZATION British Rainfall 1926-1950 .. .. .. ..208 1950 Local Organizations — The AVERAGE MONTHLY AND ANNUAL RAIN­ Staff of Observers — Investigations FALL OVER EACH COUNTY OF ENGLAND —Inspections—Inquiries—Obituary 1 AND WALES .. .. .. .. 215 2. THE DISTRIBUTION OF RAINFALL IN TIME DAYS WITH RAIN 5 LIST OF ILLUSTRATIONS 3. DROUGHTS AND DRY SPELLS 11 Relation of the Rainfall of 1950 to the 4. RAIN SPELLS AND WET SPELLS .. 17 average (coloured plate) frontispiece 5. DURATION OF RAINFALL 24 • Distribution of Wet-Days in 1950 (map) 6 6. HEAVY FALLS IN SHORT PERIODS. 31 Percentage of the Average in each 7. HEAVY FALLS ON RAINFALL DAYS .. 36 month in 1950 (12 maps) .. .46-57 8. MONTHLY RAINFALL 43 Percentage of the Average in the 9. SEASONAL RAINFALL 71 Seasons 10. TOTAL RAINFALL IN 1950 76 Winter Half-Year, 1949-1950 (map) 71 11. EVAPORATION AND PERCOLATION .. 80 Summer Half-Year, 1950 (map) 72 PART H Twelve months, October, 1949 September, 1950 (map) 73 EXPLANATORY NOTE 87 COUNTY INDEX TO GENERAL TABLE .. 89 Distribution of Total Rainfall in 1950 (map) 77 GENERAL TABLE : THE RAINFALL OF THE YEAR 90 Divisions used in British Rainfall (map) 86 111 List of Principal Tables TABLE PART I PAGE TABLE PAGE 2A WET-DAYS OVER ENGLAND AND ?A MAXIMUM DAILY FALL AND WALES, 1940-1950 .. .. 7 MAXIMUM PERCENTAGE, 1935- 2s NUMBER OF RAIN-DAYS AND OF 1950 .. .. .. .. 36 WET-DAYS, 1950. (MONTHLY ?B LARGEST DAILY RAINFALLS IN 1950 37 AND ANNUAL VALUES AT 82 SA GENERAL RAINFALL FOR 1950 STATIONS) .. .. .. 8 MONTHLY AND ANNUAL VALUES 43 SA NUMBER OF DROUGHTS AT 82 SB GENERAL MONTHLY AND ANNUAL STATIONS, 1943-1950 .. .. 12 AVERAGES OF RAINFALL, 1881- SB NUMBER OF DRY SPELLS AT 82 1915 .. .. .. ..44 STATIONS, 1943-1950 .. .. 12 8c MONTHLY RAINFALL AT 334 STATIONS, 1950 .. 3c PERIODS OF DROUGHTS AND DRY .. .. 58 SPELLS AT 82 STATIONS, 1950 13 80 MONTHLY RAINFALL IN 1950 AS • PERCENTAGE OF AVERAGE (123 4A NUMBER OF RAIN SPELLS AT STATIONS, TOGETHER WITH 82 STATIONS, 1943-1950 .. 18 GENERAL VALUES) .. .. 67 4s NUMBER OF WET SPELLS AT 82 9A SEASONAL RAINFALL, 1949-1950, STATIONS, 1943-1950 .. .. 18 IN RELATION TO AVERAGE .. 74 4c RAIN SPELLS AND WET SPELLS AT 9s GENERAL VALUES OF SEASONAL 82 STATIONS, 1950 .. .. 19 RAINFALL, 1949-1950 .. .. 75 SA DURATION OF RAINFALL, 1950. 10A GENERAL RAINFALL 1950 COM­ (MONTHLY AND ANNUAL VALUES PARED WITH AVERAGE .. 76 AT 145 STATIONS) .. .. 26 10e RAINFALL OF 1950 AT 93 STATIONS SB MEAN RATE OF RAINFALL, 1950. AS PERCENTAGE OF AVERAGE .. 79 (MONTHLY AND ANNUAL VALUES HA EVAPORATION AT CAMDEN SQUARE, AT 15 STATIONS) .. .. 30 LONDON. (MONTHLY AND AN­ 6A LOWER LIMITS OF INTENSE RAIN­ NUAL EXTREMES, 1885-1950) .. 80 FALLS .. .. .. .. 31 HB EVAPORATION IN 1950 AT 16 STATIONS .. .. 6s NUMBER OF NOTEWORTHY RAINS .. 81 OF Two HOURS' DURATION OR lie RAINFALL, PERCOLATION AND CAL­ LESS, 1950 .. .. .. 32 CULATED EVAPORATION, 1950 .. 83 6c HEAVY FALLS IN SHORT PERIODS llo DRAINAGE GAUGE RECORDS, 1950 84 IN 1950 .. .. .. .. 34 6D NUMBER OF DAYS ON WHICH SPECI­ PART H FIED AMOUNTS OF RAIN FELL IN COUNTY INDEX TO GENERAL TABLE 89 SPECIFIED TIMES, 1950 .. .. 35 GENERAL TABLE .. .. .. .. 90 IV BRITISH RAINFALL 1950 PART I 1 The Work of the British Rainfall Organization " BRITISH RAINFALL 1950." The present the Hertfordshire Natural History Society ; volume is in the same form as that for 1949 Mr. C. W. Boddington of the Northampton­ and retains the main features of pre-war shire Natural History Society ; Mr. R. S. volumes, thus enabling comparison to be Copeman of the Norfolk Rainfall Organiz­ made between the rainfall of 1950 and that ation ; the Librarian, North Devon Athen­ in earlier years. This comparison is facilitated aeum ; Mr. E. L. Kelting of the Mid-Wessex by continuing to number the principal tables Rainfall Association ; and Mr. D. W. Bogle according to their sequence in the various of the Cornwall Rainfall Association. sections. The series of maps showing Mr. Robert Burrow, Engineer and Manager monthly, seasonal and annual percentages of of the Jersey New Waterworks Company, average have been continued, the annual map forwarded returns from several stations in appearing as a coloured plate wherein the Jersey, and Mr. W. N. McCall, Burgh scale of tints of blue for more than average Engineer of Kilmarnock, continued the and of red for less than average has been collection of records in Ayrshire. continued. The exchange of information with Captain Two special features will be found in Part W. N. McClean in connexion with his work III. The first is a summary of the descriptive on River Flow was continued. articles which have been published in the There was also an exchange of rainfall data volumes of British Rainfall from 1926 to 1950. with the Director of the Meteorological This summary brings up to date similar Service of the Irish Republic. summaries for the years before 1926 published in British Rainfall for 1900 and 1926. The THE STAFF OF OBSERVERS. The second special feature is a statement of the basis of discussion of the rainfall which is average monthly and annual rainfall during presented in this volume is the collection of the period 1881-1915 for each county of about 5,500 returns of rainfall received from England and Wales. all parts of the country. Not all of these are included in the General Table (Part II of this LOCAL ORGANIZATIONS. Most of the volume), the Table being shortened by the rainfall returns from which this volume has omission of returns from check gauges and been compiled are sent by the observers of some records which are not complete. direct to the Meteorological Office, but in Returns are contributed by private persons some regions there are local organizations who measure the rainfall primarily as a who have greatly assisted by collecting rainfall matter of personal interest, or by public returns for forwarding to the Office and by local authorities and especially the authori­ stimulating interest in weather recording. ties of water undertakings who find that a Among the officials of such organizations knowledge of rainfall is essential to them in there should be mentioned Mr. R. Butler of their work. The goodwill of the observers 1 BRITISH RAINFALL 1950 who voluntarily forward copies of their Northern Ireland during the decade 1940-49," observations for preservation is gratefully was published in the Quart. J. R. Met. Soc., acknowledged. Without their co-operation Vol. 77, 1951, p.307, and another on " Abso­ the compilation of this volume would not lute Droughts of August 1947" in the have been possible. Meteorological Magazine, Vol. 79,1950, p. 260. The total number of records printed in An article " The Reliability of Rainfall over Part II of this volume is 5,043, an increase the British Isles (Third Paper), Frequency of 99 over 1949. As many as 398 additional Distribution" was discussed at the winter records are included, while 299 records meeting (1950-51) of the Institution of Water printed in British Rainfall 1949 have dropped Engineers and another on " Rainfall, Run-off out of the table. and Evaporation " at the Public Works and The net gain in England was 11, in Wales 41, Municipal Services Congress and Exhibition, in Scotland 35 and in Northern Ireland 12. Olympia, under the auspices of the British A number of additional rainfall records are Waterworks Association, in November, 1950. included in this volume and the following are In May 1951 the Director of the Meteoro­ of special interest : four records maintained logical Office arranged for the formation of a by the Taunton Waterworks near Clatworthy, hydrology section to undertake a programme to the south-east of the Brendon Hills ; of work on practical problems, based on eleven from rain-gauges at altitudes of a comprehensive picture of the complete 800-1,400 feet set up by the Montgomery hydrological cycle rainfall, evaporation, County Council in November 1949 ; eight percolation and run-off. Although records of for the Daer Valley maintained by the evaporation and percolation have been Lanarkshire County Council ; eight main­ published regularly in British Rainfall, dis­ tained by the North of Scotland Hydro- cussion previously has been limited to Electric Board ; seven received through the consideration of rainfall only, and, as a Government of Northern Ireland ; two in the matter of policy, definitely not extended to Cheviot Hills maintained by the Northumber­ cover such matters as evaporation, percolation, land and Tyneside River Board ; and isolated run-off or cognate questions.