ENG-1966 — Page 311

GEOGRAPHY AND CLIMATE

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rainfall measured at the Royal Observatory has varied between 901.1 mm (35.48 inches) in 1963 and 3040.7 mm (119.71 inches) in 1889, but the mean value is 2168.8 mm (85.39 inches). On average the six dry months from October to March yield only about one seventh of the year's total rainfall. There is a marked diurnal variation of rainfall in summer, with a maximum in the morning, and there are appreciable differences in the rainfall in different parts of the Colony. The wettest areas are the mountainous regions around Tai Mo Shan and on Lantau Island.

The mean daily temperature ranges from about 15°C in February to about 28°C in July and the average for the year is 22°C. February is normally the coldest month and July the hottest. The absolute minimum and maximum temperatures ever recorded at the Royal Observatory were 0.0°C and 36.1°C respectively. However, greater extremes may occur in the New Territories where ice occasionally forms on high ground. Afternoon temperatures are usually about 5°C higher than those during the coldest part of the night. The mean relative humidity exceeds 80 per cent from mid-February until early September. November is the least humid month with a mean relative humidity of 69 per cent, but the lowest reading of 10 per cent was recorded in January. The average daily duration of bright sunshine ranges from three hours in March to over seven hours in mid-July and late October.

Gales caused by tropical cyclones may be expected in any of the months from May to November, but are most likely from July to September. The passage of these cyclones several times a year at varying distances from Hong Kong brings spells of bad weather with strong winds and heavy rain. Gales are experienced once a year on average, and less frequently the centre of a mature typhoon passes sufficiently close to the Colony to produce winds of hurricane force when damage and loss of life may occur.

THE ROYAL OBSERVATORY

The Royal Observatory is the sole source of meteorological information in the Colony and also forms part of a world-wide network of meteorological services. Weather forecasts and informa- tion are supplied by a central forecast office. Meteorological obser- vations are made at the observatory itself in Kowloon, at the airport