The Pamphlet Collection of Sir Robert Stout: Volume 12
Chapter VIII. — Meteorology
Temperature.—Our mean annual temperature is 50-6°; our mean summer 57.5°, our winter 43.07°, Fahr.*
London has a mean annual of 51.0°, a mean summer of 64.0°, a mean winter of 37-0°. The mean annual for Edinburgh is 47.0°, the mean summer 38-0°, and the mean winter 37.0°. For Dublin, the mean annual is 50.0", summer 61.0°, winter 39.0°. In the south-west district of Wales the mean annual is 54.0°, the mean winter being as high as 42.0°. Auckland has a mean annual of 59.0°, Melbourne of 57.0°, Hobart Town of 52.0°, and Sydney of 66.0°.
* Calculated from Government Tables.
The mean daily range of temperature for Dunedin averages for a year 14.0° Fahr. For a period of seven, the highest mean daily range was 22.0°, the lowest was 8.0°, the former being for a January month, the latter being for a June month. In Scotland 12° is the average mean daily range.*
The physical features of a country have a modifying influence on its climate, in addition to its latitude. Thus our ocean and forests control the mean daily range of temperature, and influence the humidity of our atmosphere.
Rainfall.—Our mean annual rainfall is 31.49 inches. Rain falls on an average upon 148 days in the year, 69.2 of these being what are termed rainy days-i.e., over 0.1 in. falls upon them.
The average rainfall in a year among the western hills of Great Britain and Ireland is 80 to 150 inches; away from the hills, likewise upon the west, 30 to 45 inches; and upon the east it is 20 to 28 inches. In France 30 inches is the yearly average. During our summer months, from the years 1867 to 1873 inclusive, a mean of 9.840 inches of rain fell, the mean for the winter months being 8.323 inches-the greatest rainfall any one day amounting to l.926, with a south-east wind, in a May month.
The mean dew point for seven years, as taken at the Government Observatory, was 42.5°.
The mean humidity for the same period was 76.3°, saturation equalling 100. Our atmosphere is as a rule ¾ saturated with vapour,†
The prevailing wind is the west, next south-west, and northeast.
* Buchan on Meteorology.
† Taking the atmosphere around the Observatory to be not far different from that in the City.