ENG-1975 — Page 244

THE ENVIRONMENT

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in the northern part of the South China Sea. Thunderstorm and heavy rain warnings were issued on 19 days.

June was an extremely wet month with 579.6 mm of rain. The southwest mon- soon was very active, resulting in thunderstorm and heavy rain warnings being issued on 14 days. There were landslips and flooding in low-lying areas. July was sunnier and drier than usual. It was the first month since February with below average rainfall. More than 80 per cent of the month's total rainfall of 292.4 mm fell between July 12-6 when there was some flooding in the New Territories. Two tropical cyclones were reported over the western North Pacific but they did not affect Hong Kong.

There were more heavy showers and thunderstorms in August and the month's total rainfall of 458.9 mm exceeded the average figure for August by 24 per cent. Although there were five tropical cyclones over the western North Pacific and the South China Sea during August, only one necessitated the hoisting of warning signals in Hong Kong. The tropical depression developed about 220 miles to the south of Hong Kong during the night of August 9 and moved towards Hainan Island. But when it reached the southwestern tip of Hainan Island, it turned round and moved back towards the Pearl River Estuary. The eye of the depression covered an area of about 40 miles in diameter and its eastern part passed over Hong Kong on August 14. It finally degenerated into an area of low pressure near Canton.

September was warmer and much drier than usual with a total recorded rainfall of only 96.0 mm. Four tropical cyclones were reported and warning signals were hoisted for two of them-severe tropical storm Alice and typhoon Betty. The fine and sunny weather ahead of Betty caused the air temperature on September 22 to rise to a maximum 33.9°C, which was the highest temperature recorded in 1975.

In October there were five tropical cyclones reported, and three necessitated the hoisting of tropical cyclone warning signals. Temperatures were near normal but humidity was unseasonably high. The month's total rainfall of 465.6 mm was about 34 times more than usual and ranked as the fourth highest on record.

November was much drier than usual with only 17.4 mm of rainfall. Although three tropical cyclones were reported during the month, none came close enough to threaten Hong Kong. Dry conditions prevailed for the last 14 days of the month and fire danger warnings were in force for the entire period. The strong monsoon signal was hoisted once, from November 22-4, to give warning of strong to gale force northerly winds due to an intense surge of the winter monsoon. As a result, air temperatures fell steadily and the minimum temperature of 8.5°C recorded at the Royal Observatory on November 24 was the lowest for any November since 1922 and ranked fourth lowest on record.

Severe outbreaks of the winter monsoon associated with an exceptionally intense continental anticyclone centred over Siberia resulted in very cold weather in Decem- ber. The mean temperature for the month was only 14.5°C, the lowest on record for December. On the morning of December 14, the Royal Observatory recorded a minimum temperature of 4.3°C, which was the lowest temperature recorded in the year and was also a new record for December. The minimum temperatures recorded