ENG-1955 — Page 221

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HONG KONG ANNUAL REPORT

storm or typhoon moves into the China Sea, 6-hourly, and often 3-hourly, statements of position, intensity and direction of movement of the centre are issued. Frequent reliable ship reports and storm reconnaissances by United States aircraft help locate storms accurately. When the Colony itself is threatened, the local storm warning system is brought into use, and warnings are widely distributed by means of visual signals, telephone, radio and Rediffusion. Although Japan suffered severely from typhoons during the year, the China Sea was little affected. The local strong wind signal was hoisted twice in Hong Kong, but no typhoon signals were displayed.

In addition to its meteorological activities, the Royal Observatory operates a seismological station and a time service.

METEOROLOGICAL RESEARCH

In May and June, with willing cooperation from other Government Departments, the Armed Forces and private individuals, the Observatory mounted a 6-week test of the water injection method of stimulating rainfall from cumulus clouds. Although much rain fell during the test, careful checking revealed that the method is ineffective in Hong Kong.

During the partial solar eclipse of 20 June, serial radiosonde ascents made from King's Park confirmed the validity of the standard radiation and lag corrections applied to temperature readings from the Kew Mark II B radiosonde.

A new and enlarged edition of "A statistical survey of typhoons and tropical depressions in the western Pacific and China Sea area" is being prepared for publication in 1956. It will depict storm tracks for the years 1884 to 1953.

Papers by Observatory staff which appeared during the year included works on the cool season tropical disturbances of South-East Asia (in the Journal of Meteorology, Vol. 12, No. 3, June 1955, Lancaster, Penn.), a Hong Kong fore- caster's manual (Royal Observatory Technical Note No. 10), an analysis of low cloud and poor visibility at Hong Kong Airport, 1949-54 (Technical Note No. 11), median and quartile upper air temperatures at given pressure-levels at Hong Kong, 1949-55 (Technical Note No. 12), and on artificial and orographic stimulation of rainfall in Hong Kong (Technical Note No. 13).