GEOGRAPHY AND CLIMATE
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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% from mid-February until early September. November is the least humid month with a mean relative humidity of 69%, but the lowest reading of 10% 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 they 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.
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THE ROYAL OBSERVATORY
The main function of the Royal Observatory today is the provision of meteorological services. Weather forecasts and tropical cyclone warnings are prepared in the Central Forecasting Office at the Royal Observatory in Kowloon while services for aviation are provided at the Airport Meteorological Office. Regular meteorological observations are made at the Royal Observatory, at the Airport and at six other points in the Colony. Upper-air soundings of the atmosphere are made at King's Park Meteorological Station where balloons carrying special reflectors are released every six hours and tracked by wind-finding radar. Two balloons each day carry a radiosonde transmitter to measure the pressure, temperature and