After fine, clear weather the first signs in a sky of a coming change are usually light streaks, curls, wisps, or mottled patches of white distant cloud, which increase and are followed by an overcasting of murky vapour that grows into cloudiness. This appearance, more or less oily or watery as wind or rain will prevail, is an infallible sign.
Usually, the higher and more distant such clouds seem to be, the more gradual, but general, the coming change of weather will prove.
Misty clouds, forming or hanging on heights, show wind and rain coming, if they remain, increase, or descend; if they rise or disperse, the weather will improve or become fine.
| May be Expected | |
| ----- | |
| Fine weather | When the sky is grey in the morning. |
| Wind | With a high dawn. |
| Fair weather | With a low dawn. |
| Wind | When the sky at sunset is of a bright yellow. |
| Rain | When the sky at sunset is of a pale yellow. |
| Wind and rain | When the sky is orange or copper colour. |
| Fine weather | When the sky has light, delicate, quiet tints and soft, indefinite forms of clouds. |
| Rain and wind | When the sky has gaudy, unusual hues, with hard, definite outlined clouds. |
| Fair weather | When sea-birds fly out early and far to seaward. |
| Stormy weather | When sea-birds hang about the land, or fly inland. |
| Fair weather | When dew is deposited. Its formation never begins under an overcast sky, or when there is much wind. |
| Rain | On what is called a good hearing day. |
| Rain | When remarkable clearness of atmosphere, especially near the horizon, exists, distant objects, objects, such as hills, being unusually visible or well defined. |
RAIN.
The atmosphere at a given temperature is capable of retaining only a given quantity of aqueous vapour, invisibly diffused through it, at which temperature it is said to be saturated. Should the temperature from any cause be lowered, the aqueous vapour at once becomes visible in the form of either cloud, dew, rain, snow, or hail. It has already been shown that, although marshes and rivers, inland seas and lakes, yield by evaporation watery vapours to the air, the ocean is the great source of rain, whence it is lifted in vast quantities by the sun’s radiant heat, to be subsequently condensed by passing into cooler regions, or by contact with cold mountain peaks, falling to earth as a fertilizing shower or a devastating flood.
Sir John Herschel accounts for the formation of raindrops by saying:—“In whatever part of a cloud the original ascensional movement of the vapour ceases, the elementary globules of which it consists being abandoned to the action of gravity, begin to fall. The larger globules fall fastest, and if (as must happen) they overtake the slower ones, they incorporate, and the diameter being thereby increased, the descent grows more rapid, and the encounters more frequent, till at length the globule emerges from the lower surface of the cloud at the ‘vapour plane’ as a drop of rain, the size of the drops depending on the thickness of the cloud stratum and its density.”
Rain is very unequally distributed, there being portions of the torrid zone where it never falls, one locality in Norway where it falls three days out of four, and another on the western side of Patagonia, at the base of the Andes, where it falls every day. The quantities recorded as having fallen at one time in some localities are simply appalling. A fall of one inch is considered a very heavy rain in Great Britain, and this fact will enable the reader partially to realize the following stupendous recorded falls:—Loch Awe, Scotland, 7 inches in 30 hours; Joyeuse, France, 31 inches in 22 hours; Gibraltar, 33 inches in 26 hours; hills above Bombay, 24 inches in one night; and on the Khasia Hills, where the annual rainfall is 600 inches, 30 inches have been known to fall on each of five successive days. Mr. G. J. Symons, the able editor of the “Meteorological Magazine,” and indefatigable superintendent of 2,000 Rain Gauges throughout the United Kingdom, has compiled a table, showing the equivalents of rain in inches, its weight per acre, and bulk in gallons, the following portion of which, while very useful to the farmer, will enable the curious reader to make some interesting calculations, based on the figures quoted above:—
Table showing equivalent of inches of rain in gallons,
and weight per acre.