ENG-1965 — Page 286

GEOGRAPHY AND CLIMATE

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soundings of the atmosphere are made at the radiosonde station at King's Park, where balloons carrying special reflectors are re- leased every six hours and tracked by windfinding radar. One balloon each day carries a radiosonde transmitter which transmits back the pressure, temperature and humidity at all levels through which the balloon ascends. Numerous rain-gauges are operated throughout the Colony by government employees and private individuals on behalf of the observatory.

At the airport the pilots of all aircraft leaving Hong Kong are briefed and provided with written forecasts. Information is also exchanged with other centres, and radioed to aircraft in flight. Special weather bulletins are broadcast for shipping and local 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 observations.

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 help to locate the storms accurately. When the Colony itself is threatened the local storm warning system is brought into use and warnings together with announce- ments about necessary precautions are widely distributed and broadcast at frequent intervals. A new weather radar has recently been ordered for use in the storm warning service.

Time signals originating at the observatory are sent out over Radio Hong Kong and included in special broadcasts for shipping. In order to improve the accuracy of these signals a new crystal controlled chronometer has been ordered to replace the synchronome pendulum clock that has been in use since 1950. The observatory operates 12 seismometers, distributes weekly and monthly reports and also takes part in the Pacific tidal wave warning service. Hong Kong lies some distance from the circum-Pacific seismic belt and