ENG-1976 — Page 278

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THE ENVIRONMENT

Unlike the previous five months, June was wetter than normal with rainfall about six per cent above average. The southwest monsoon affected south China and the northern part of the South China Sea and the weather in Hong Kong was mainly cloudy with occasional heavy showers and scattered thunderstorms. The rainfall recorded on the two days June 2-3 contributed almost half the month's total. Typhoon Ruby, which affected Hong Kong from June 26-9, was the first tropical cyclone for which warning signals were displayed during the year.

The weather in July was seasonable although rainfall was about 15 per cent above average. Of the four tropical cyclones that developed over the western North Pacific, only severe tropical storm Violet affected Hong Kong, causing frequent heavy showers and isolated thunderstorms.

Apart from the excessive rain caused by tropical storm Ellen, August was generally warm and sunny. The total rainfall of 765.3 mm was more than double the average figure and ranked as the third highest on record for any August. The 24-hour rainfall of 416.2 mm recorded between 11 am on August 24 and 11 am on August 25 was the highest in any August and the third highest in any month. The two-day total of 511.6 mm recorded on August 24 and 25 created a new two-day record for August and it has only been exceeded on two previous occasions in other months. Another tropical cyclone that brought heavy rain to Hong Kong was severe tropical storm Clara, which passed about 70 miles southwest of Hong Kong on August 6.

September and October were abnormally cloudy but with below average rain- fall. Typhoon Iris affected Hong Kong from September 18-21 and caused sustained gales. Iris degenerated into an area of low pressure on September 21 over the north- eastern part of the Gulf of Tonkin and remained almost stationary in the vicinity of Hainan Island until the end of the month. During this period the strong monsoon signal was hoisted on three occasions for a total duration of 148 hours 15 minutes, which is the highest monthly figure since 1956 when this signal was first introduced.

Because of the persistence of an intense anticyclone over north China, November was exceptionally cold and dry with the lowest mean temperature on record. The total rainfall in the month was only 2.0 per cent of the average and, although fire danger warnings were in force almost every day, there were many disastrous fires both in the urban areas and in the New Territories.

Due to the collapse of the continental anticyclone over north China, Hong Kong had a long spell of mild and sunny weather in December. Daily mean tempera- tures remained well above normal on almost every day until the arrival of an intense cold surge late on Christmas Day. The air temperature than fell steadily and on the morning of December 28 a minimum temperature of 5.7°C was recorded-the lowest of the year. Warnings of ice and frost were broadcast so that farmers could protect their crops and livestock. During the three days December 27-9 rime was observed near the top of Tai Mo Shan, where a minimum temperature of -3°C was registered on December 28. Frost was also reported on high ground and in the northern parts of the New Territories. Damage to crops was slight but many young fish in the fish ponds in the New Territories were killed and there was considerable loss of livestock.