ENG-1966 — Page 313

GEOGRAPHY AND CLIMATE

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disturbance up to 240 miles away from Hong Kong, was installed at the station during August.

Beginning from September this year, the observatory used a new crystal-controlled timing system to provide time signals for ships, aircraft and the public, accurate to within 0.05 seconds. Time signals are broadcast every quarter of an hour on a frequency of 95 MHz (frequency modulated) and can be intercepted by a domes- tic FM receiver. In addition, visual time signals are flashed from the observatory during the hours of darkness by three white lights at times coinciding with the times of broadcast. The observatory operates 12 seismometers, distributes weekly and monthly reports of earthquakes and also participates in the Pacific tidal wave warn- ing service. Hong Kong lies some distance from the circum-Pacific seismic belt and serious earthquakes are unknown. However, a few tremors have been felt by people in favourable locations every year. Four such tremors occurred in 1966.

The general level of atmospheric radioactivity in the Colony is monitored at King's Park, where routine measurements of the 'Beta' and 'Gamma' activities of fallout, airborne particles near the ground, rainfall and ordinary tap water are carried out. The observatory acts in an advisory capacity in the planning of a great many projects that may be affected by meteorological conditions, and publishes numerous reports, bulletins and papers on meteorological and geo- physical observations and research activities.

RESEARCH AND APPLIED METEOROLOGY

Numerous minor investigations of a climatological and statistical nature were completed during the year for aviation and local engineering interests or for use within the department. A detailed analysis of the occurrence of various rainfall amounts was completed with the aid of an electronic computer installed at the University of Hong Kong. The results were included in a Report on the Maxi- mum Probable Rainfall over Hong Kong, which was prepared to meet the planning and design requirements for new reservoirs. The study of the spectrum of turbulence in typhoon winds and the structure of the tropopause in the eye of a tropical cyclone con- tinued. An investigation into the effects of strong winds on the different types of rain-gauges used in the Colony was started, and