WEATHER FORECASTS

Wanganui Chronicle, Volume 75, Issue 117, 20 May 1932, Page 9

WEATHER FORECASTS

NORTHERN HEMISPHERE ’ , GREAT PROGRESS MADE Dr. G. U. Simpson, who wau in New Zealand when physicist to the British Antarctic Expedition, 1910-13, and who has been Director of the Meteorological Office since 1920, delivered a lecture before the Royal Institution recently, when he mentioned that the first weather forecasts were issued 1861 by Admiral Fitzroy, then head of a Board of Trade department, estub lished to study marine meteorology. With Fitzroy’s death in 1865 they ceased, and the service was not recommenced till 1879.

During and since the war great advances, ho said, had been made in our knowledge of the structure of the atmosphere. It was now recognised that weather was produced by the bringing together of great masses of air from polar and tropical legions by the general circulation of the atmosphere. Such masses of cold and warm air did not readily mix, but. over-ran or undercut one another along “fronts” which could be traced for hundreds of miles on the synoptic charts. On one side of a “front” there was warm air and on the other side cold air, and cyclones were complicated meeting points of warm and cold “fronts.”

“As warm air slides up over cold air, or cold air cuts under warm air, cloud and rain are formed, so that ‘fronts* are long, and usually narrow, strips of bad weather, and it is the motion of the ‘fronts’ which is now the chief concern of the forecaster. The recognition of ‘fronts’ has given the forecaster a powerful new tool for the study of what, is actually taking place in the atmosphere, and has greatly improved the short period forecasts, especially those for aviation.” At certain specified times each day observations are taken at 45 stations in the British Isles and on a number of ships in the Atlantic and telegraphed to London. By close co-oper-ation information from over 500 stations is available in every meteorological office in Europe within two hours of the observations being taken. There is no intelligence service in the world so complete and so rapid as the international weather service. The service on the civil air routes is even more elaborate and takes the place of the elaborate signalling system of a railway. Discussing the success of forecasting. Dr. Simpson said: “If the only pur ! pose of a meteorological service wero| to tel! the public when to take ar umbrella or when to leave an overcoat at home, it is questionable whether the cost of the service woubj •? justified. The object is, however, to supply weather information to those whoso work, and often life, depends on the weather. Forecasts for shipping, for fishermen, for aviation, and for agriculture are the justification for the elaborate meteorological services maintained in all countries. No method has yet been found for expressing the success of weather forecasts by giving the percentages of failures anad successes, but the improvement in the supply- of information and the scientific discover,!es have resulted in an. appreciable increase in the. accuracy of the forecasts.”