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SUPPLEMENT TO THE HONGKONG GOVT GAZETTE OF 17TH APR., 1886.
Table X exhibits the total distance traversed by, as well as the duration and average velocity c winds from bi-quadrantal points. The velocity is a maximum for E winds and the average directio is straight E, but there is a secondary maximum for SW winds, whose duration is however smal Both with regard to frequency and velocity the S and SW winds in 1885 were greater than in 1884.
Table XI shows particulars concerning the rainfall, (as measured at 10 a.) which in the summe was considerably greater at the Peak than at a lower level. Each day on which not less than 0.01 inche of rain fell, is counted. It is plain, that the observers neglect to measure the rain every day at the Pea and at Stone Cutters' Island.
Table XII contains particulars concerning different phenomena. Fog occurred frequently i March. At times when gradients are slight and clouds come from between SE and SW fog may b expected. Electric phenomena are most frequent in August, but as many thunderstorms passed ove the Colony in April, as in August. The storms were severer and lasted about twice as long as in th previous year. Some damage to property was caused by them, but not so much as would be caused by an equal number of storms of equal severity in the United Kingdom. They have a well marked dail period, being most frequent at 7 p.
Their direction was generally from W towards E up to the en of April and subsequently from SW towards NE. Unusual visibility of distant objects was mos frequent in June, when the air was moist and fog absent. Halos were frequent in July.
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Table XIII shows the frequency of clouds of different forms from observations made 8 times a day During January, cum. prevailed, during February and March, cum-nim. In April cum. again prevail and holds the ground till the end of the year.-C, c-str. and c-cum. have their maxima in the typhoon season, the latter forms already in July. Sm-cum. are common during the last half of the year, wher the weather is fine. Cum-str., the thunderclouds, had their maximum in July, R-cum in winter cum-nim, the threatening cloud, in spring, and nim, the rain cloud, in the rainy season.
The number of days on which clouds were observed to be below 2000 feet was as follows:— January, 14, February, 19, March. 19, April, 24, May, 20, June, 14, July, 18, August, 14, September 10, October, 2, November, 2, December, 12-The number of days on which they were observed to be below 1000 feet was as follows:--January, 2, February, 10, March, 8, April, 5, May, 6, June, 0 July, 2, August, 1, September, 1, October, 0, November, 0, December, 3.
The mean direction of clouds (whence coming) was as follows:---
1885.
January,.
Lower.
Upper.
Cirrus.
E by S
W
W
February,
E by N
W
W
March,
ESE
W by S
W
April,
SE
W
W
May,
S
WNW
WNW
June,.
S
NNW
N
July,
SSW
NNE
N
August,....
S
NNE
NNE
September,
SSE
NNW
NE
October,
ENE
W
NNE
November,
ENE
W
December,...
E by S
W
W
In computing the direction of the upper clouds, cirri were included, and in computing the direction of cirrus the observations made in 1884 were also included. From June to October inclusive cirri come from two different directions,-from about NE while a typhoon is in existence somewhere, their direction often backing from E to N while the typhoon is yet over 700 miles away; and from about W, when there are no signs of a typhoon. But cirrus is rarely seen in summer except before typhoons, through whose agency vapour is evidently brought up to the higher regions of the atmosphere.
The c-str. radiate most frequently from NE, and so far I have not succeeded in connecting the direction of the strice with the position of typhoons.
It is possible, that the direction whence coming of the clouds has a slight diurnal variation. The direction appears to back one or two points during the day. This is just the reverse of the diurnal variation in the direction of the wind, which would agree well with the hypothesis advocated by Espy and Köppen.
The direction whence coming, of the lower clouds is to the right of the wind to an observer facing the wind, especially in summer. In September, the direction of the wind changed most quickly with the elevation, the mean direction of the wind at the Observatory being E by N, at the Peak ESE, at the level of the lower clouds SSE, at the level of the upper clouds NNW, and at the level of cirrus, perhaps 6 or 8 miles up, NE.
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