ENG-1969 — Page 303

GEOGRAPHY AND CLIMATE

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winter monsoons were completed and published. Objective techni- ques for forecasting the movement of tropical cyclones continued to be tested and improved. In an attempt to reduce the number of accidental grass fires caused by members of the public, an investi- gation into the relationship between the occurrence of these fires and various meteorological parameters were carried out. Warnings were issued by the Royal Observatory whenever necessary.

The Royal Observatory continued to co-operate with several other overseas scientific institutes in many special research projects in seismology, radio-activity, marine climatology and atmospheric chemistry.

THE YEAR'S WEATHER

Slightly less than the normal number of tropical cyclones occurred in the western Pacific and the South China Sea during the year and many of the Pacific typhoons recurved towards the north-east near Taiwan or the Philippines. Consequently, although local storm signals were hoisted on four occasions, no gales were experienced in Hong Kong. The year, in general, was warmer, sunnier and drier than usual. The annual rainfall, 1895.5 mm (74.63 inches) was only 87 per cent of the normal amount.

Dull and humid weather persisted during most of January and February. Altogether seven cold fronts passed through the Colony in these two months and the most intense one brought the air temperature down to 4°C at the Royal Observatory on February 5. On the same morning, a minimum temperature of -5.5°C was recorded on top of Tai Mo Shan and -2.3°C at Tate's Cairn; some hillsides were white with rime.

March and April were colder than usual. Thunderstorms were experienced on several occasions during the first 11 days of March and were followed by alternating spells of foggy and cold weather. On April 4, a late burst of the winter monsoon caused a sharp drop in temperature and humidity and the minimum tem- perature of 9.9°C on April 5 was the lowest on record for that month. Moreover the minimum relative humidity of 23 per cent was the second lowest ever recorded in April. On April 12, warm moist air from the south brought heavy showers and thunderstorms to Hong Kong and flooding was reported in many places. During