ENG-1966 — Page 312

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GEOGRAPHY AND CLIMATE

and at six other points throughout the Colony. Upper air soundings of the atmosphere are made at the King's Park meteorological station, where balloons carrying special reflectors are released every six hours and tracked by windfinding radar. One balloon each day carries a radiosonde transmitter which sends back by radio the pressure, temperature and humidity readings at all levels through which the balloon ascends. The observatory maintains the densest network of rain-gauges in South-East Asia, operated by government employees and voluntary observers.

At the airport the pilots of aircraft leaving Hong Kong are briefed and provided with written forecasts. Information is also exchanged with other weather centres and radioed to aircraft in flight. Special weather bulletins are broadcast for shipping and also for local yachtsmen and fishermen. About 60 ships are provided with instruments by the observatory and close liaison is maintained with all ships that visit Hong Kong to assist them to transmit regular and accurate weather reports. These observations are plotted and analysed at the Royal Observatory and also broadcast to other centres. After being checked against the original entries in the ships' log books, the observations are recorded on punched cards for climatological purposes.

One of the most important functions of the central forecast office is to issue warnings of tropical cyclones. Whenever a tropical depression, tropical storm or typhoon is located within the region bounded by latitudes 10°-30° north and longitudes 105°-125° east, six-hourly and often three-hourly non-local warnings are issued. These provide information on the storm's intensity and expected development, the position and movement of its centre and the forecast position for 24 hours ahead. Reliable reports from ships and reconnaissance aircraft, and cloud pictures received at the observatory from meteorological satellites, help to locate the storm accurately. When the Colony itself is threatened, the local storm warning system is brought into use and warnings are widely dis- tributed by means of visual signals, telephone, radio and Rediffu- sion. Statements and announcements about necessary precautions are also broadcast at frequent intervals when gale signals are hoisted. The observatory's weather radar station at Tate's Cairn is equipped with a 3 cm radar for the detection of showers and local rainstorms. A new 10 cm radar, capable of detecting tropical