669949-1885-Annual-Weather-Report-for-1884- — Page 1

SUPPLEMENT

To the HONGKONG GOVERNMENT GAZETTE of 28th March, 1885.

GOVERNMENT NOTIFICATION.-No. 137.

following Annual Weather Report for 1884, from the Government Astronomer, is published rad information.

By Command,

Clonial Secretary's Office, Hongkong, 28th March, 1885.

W. H. MARSH,

Colonial Secretary.

ANNUAL WEATHER REPORT FOR 1884.

The construction of accurate average values of the meteorological elements forms perhaps the t important operation in connection with the discussion of meteorological observations. Apart the insight into the nature of a climate, which is gained from a comparison of the averages with se computed by similar methods for other places in the world, it is impossible to thoroughly erstand the indications of the instruments or the features presented by the weather, unless it is wn accurately, how much the phenomena differ from their average values. But unfortunately many ars observations must be at hand, before trustworthy averages can be derived, i.e., such as are likely be equal to the averages of future years. A very different number of years is required in case of different elements, but it is generally supposed that monthly means may be formed from ten years' servations. A longer series is required for five-day means, and again a much longer series for daily ans, and there are various interesting questions especially concerning the cosmic aspects of meteor- ry, that can be answered only when trustworthy daily means are available.

From these considerations it will appear, how very imperfect must be conclusions drawn from a Single year's observations,--but on the other hand each single year has to be discussed," "before more rate averages can be obtained. In the following tables the hourly and monthly means of some of the principal elements for the past year are exhibited. Such tables as would be positively misle eting. wing to their being constructed from a single year's observations, have been suppressed in this ri poszt.

Table I shows the mean height in inches of the barometer at the Observatory and at the Penk, the ter being the mean of the 10a., 4p., and 10 p. observations, and the excess of the hourly values al

mean.

The height of the barometer undergoes daily a double variation, which is so regular, that it may perceived even during considerable disturbances, the approaches of which are indicated he danchand irregularities in the variation, and the heights of the barometer observed during the rusing of a hoon must be freed from the diurnal variation, if the progress of the disturbance is to be props lerstood.

At la. the barometer begins to rise. It is at the time comparatively lower in spring, when the osphere is saturated with moisture, than later in the year. It attains its mean height about fi haps a little later in spring than in autumn and winter. At 10 a., the height attains it- ile n ximum, which is in Hongkong the principal maximum except perhaps in June and July. barometer stands comparatively highest at 10a. in mid-winter. After 10a. it begins to fall and attain-

in its average value about 1p. in spring but shortly after noon about the latter end of th Peaches its second minimum between 4p. and 5p. in spring but already about 3p. in w Seasons of the year this is the absolute minimum but comparatively lowest in winter. ses and reaches its third average shortly before 8p. The second maximum occurs about top.

ps later in spring than in winter. This was comparatively highest in July. Then the hapone still about 3a. in spring and about 4 a. in winter, when it attains its forenoon minimum, but thi about three times as low in spring as in December. In fact in mid-winter the mean height of the neter is, considering the low latitude, remarkably constant during the night, which must 1 sed by the extreme dryness of the air and the comparatively great range of temperature.

Th

The diurnal range in the different months came out as follows: Jan. 0.101, Feb, 0,109, Mar April 0.081, May 0.079, June 0.068, July 0.061, Aug. 0.076, Sep. 0.072, Oct. 0,08, Nov

5. Dec. 0.11.