Sessional_Paper_1886-1887 — Page 282

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At the height of Victoria Peak the direction of the wind is nearly constant throughout the day. Only a slight tendency to veer during the daytime can perhaps be traced. Above this altitude as remarked in last year's report there is possibly a slight tendency to variation in the opposite direction. The force of the wind is likewise

very constant.

It seems to be rather stronger at night than in the day time but this cannot be decided as yet with certainty.

In Southern Formosa the wind comes from NE without change in winter. This is the mean direction either diurnal or annual from October till March incl. On the contrary the direction appears to be very changeable in summer. With regard to the diurnal variation in the force the result published last year is confirmed. The maximum wind-force appears to be registered about sunrise and the minimum about sunset, but the variation is very small. The diurnal variation in the direction is scarcely perceptible but from the mean of the twelve months it would even appear as if the wind were backing a little during the day time, but the veering of the wind during the day time is very prominent in summer.

Table X exhibits the total distance traversed by, as well as the duration and average velocity of winds from bi-quadrantal points. The velocity is a maximum for E winds but there is slight second- ary maximum for SW winds. The SW monsoon was not so strong as in 1885, which perhaps accounts for the scarcity of rain.

Table XI exhibits the rainfall measured at 10 a. and entered to preceding day. Each day on which not less than 0.01 inches was measured, is counted. The rainfall increases quickly with the height at least up to 2000 feet notwithstanding the far greater force of the wind up there. We have no means of observing what takes place at a still higher level but Indian Meteorologists have ascertained that the rain reaches a maximum somewhere about 4000 feet above the level of the sea in India.

Table XII exhibits particulars concerning different phenomena. Fog occurred frequently in March. Electric phenomena prevailed in August but the thunderstorms were not so violent as in 1885. Unusual visibility of distant objects was most noticeable in August. Dew was frequent during the early summer. Rainbows were seen oftener than usual owing to the lightness of the rains. Solar halos and coronas were most frequent in August.

Table XIII shows the frequency of clouds of different forms from observations made 8 times a day. The number of days on which clouds were observed to be below 2000 feet was as follows:- January, 12, February, 16, March, 28, April, 25, May, 18, June, 16, July, 22, August, 15, September, 3, October, 5, November, 0, December, 3. The number of days on which they were observed to be below 1000 feet was as follows:-January, 3, February, 10, March, 21, April, 17, May, 7, June, 3, July, 5, August, 0, September, 0, October, 0, November, 0, December, 2.

The mean direction of the clouds (whence coming) was as follows :—

1886.

January,

Lower.

ESE

Upper. WSW

Cirrus.

February,

E by S

W

March,

SE

W by S

April,

ESE by S

W by S

May,..

SE by S

W by N

W

NW by W

June,

S

NNE

July,

S by E

NE by E

ENE

August,

SW by S

NE

NNE

September,

ENE

NW by W

W by S

October,

E

WSW

NW

November,

ENE

WSW

WSW

December,

ENE

W by S

Table XIV exhibits the amount of cloud, which is greatest in the morning and least in the evening as well as greatest in February and least in December.

Table XV exhibits the amount (0-9) of sea-disturbance, which is only about half as great in summer as in winter.

Table XVI and XVII exhibit the extremes of some of the meteorological elements.

Table XVIII exhibits the mean of the readings of the black bulb maximum thermometers in vacuo and the excess above the mean maximum air-temperatures, the average of the number of degrees by which the minimum air-temperature exceeded that indicated by a minimum thermometer freely. exposed with its bulb one inch above the grass, the average weight of the aqueous vapour in the air and the diurnal range of temperature.