When the countries of temperate climates suffer under tempests in frequent succession, Polar regions enjoy comparative tranquillity. After the autumn gales have passed, a series of calm weather, attended by severe frosts, frequently succeeds. So striking, indeed, is the stillness of the northern winter, that there is truth in Dr. Guthrie’s observation, that nature seems “to have studied perfect equality in the distribution of her favours, as it is only parts of the earth which most enjoy the kindly influences of the sun that suffer by the effects of its superior heat, so that if the atmosphere of the north is not so genial as that of the south, at least it remains perfectly quiet and serene, without threatening destruction to man and the product of his industry as in what are called happier climates.”
The principal meteors, not being of the aqueous kind, that remain to be considered are lightning and the aurora borealis. As we approach the Pole, the former phenomenon becomes more rare, and the latter more common. Lightning, indeed, is seldom seen to the northward of the arctic circle, and when it does occur, it is very seldom accompanied by thunder.
In Spitzbergen, neither thunder nor lightning has, I believe, ever been observed. For my own part, I have never seen lightning northward of latitude 65°, and only in two instances when at any considerable distance from land. The aurora borealis occurs independent of land and of cold, becoming more frequent in its appearance as we approach the Pole, and enlivening by its brilliancy and peculiar grandeur the tedious gloom of the long winter nights. Its appearance, though not very frequently seen in Britain, is very common as far south as Shetland and Feroe. In Iceland, and other countries bordering on the arctic circle, the northern lights occur almost every clear night during the winter. In the summer, they can seldom be seen on account of the presence of the sun, and in the spring of the year, the obscurity of the atmosphere prevents their frequent exhibition. In several instances, I have known stormy weather follow the appearance of the brilliant aurora, and one of the most tremendous storms I was ever exposed to, succeeded a splendid exhibition of the northern lights. Under certain circumstances, especially when they are seen at a considerable altitude above the horizon, having a red or copper colour, they are supposed to be indicative of a violent storm.
Our chapter on atmospherical phenomena must now be concluded by observations on aqueous meteors; including clouds, rain, hail, snow, frost-rime, hoar-frost, and fog.
Very little clear weather occurs in the Greenland seas, for often when the atmosphere is free from any visible vapour on the land, at sea it is obscured by frost-rime in the spring of the year, and by clouds or fog in the summer; so that scarcely one-twentieth of the season devoted to the whale-fishery can be said to consist of clear weather.
The clouds most generally consist of a dense stratum of obscurity, composed of irregular compact patches covering the whole expanse of the heavens. The cirrus, cirrocumulus, and cirrostratus, of Howard’s nomenclature, are occasionally distinct; the nimbus is partly formed, but never complete: and the grandeur of the cumulus or thunder-cloud is never seen, unless it be on the land. In the atmosphere over the coasts in Greenland and Spitzbergen, where the air is greatly warmed by the concentration and reflection of the sun’s rays in the sheltered valleys, a small imperfect cumulus is sometimes exhibited.
The known agents made use of in the economy of nature for the production of rain are changes of temperature and electricity. The latter principle is supposed to act most powerfully in the production of thunder-showers, in which case it is not unlikely that a portion of the air of the atmosphere is, by the passing of the lightning from one cloud to another, converted into water. The former seems to be the chief agent in the colder regions of the globe, where electricity is either more equal in its distribution, or not so active in its operations as in the warmer climates. From the beautiful theory of the late Dr. James Hutton, supported by the researches of professor Leslie, it appears, that “while the temperature advances uniformly in arithmetical progression, the dissolving power which this communicates to the air mounts with the accelerating rapidity of a geometrical series;” and this in such a ratio, that the “air has its dryness doubled at each rise of temperature answering to fifteen centesimal degrees,” or twenty-seven of Fahrenheit. Hence, “whatever be the actual condition of a mass of air, there must always exist some temperature at which it would become perfectly damp;” and hence whenever two streams of air saturated with moisture of different temperatures are mixed together, or brush against one another, in the form of different currents of wind, there must always be a quantity of moisture precipitated. For if two masses of air, of different temperatures, but equal in quantity, and both saturated with moisture, were mixed together, the resulting temperature would be nearly the mean of the two, but, at that temperature, the capacity of air for moisture being less than the quantity contained in the two commixed masses, the surplus must be deposited.
Rain is by no means common in the Polar countries excepting in the months of July and August, and then only with southerly or westerly winds. During all seasons of the year, however, with strong gales blowing from a southern climate, rain is occasionally observed in situations near the edge of the ice; but snow or sleet are more common even under such circumstances; and in remote situations among ice, near the 80th parallel of latitude, rain seldom or never occurs.
Hail is a much more familiar meteor in temperate than in frigid climates. In the Greenland Sea, this aqueous concretion is very rarely seen; and if we define it as consisting of pellucid spheres of ice, generated in the atmosphere, it may be said to be unknown in very high latitudes. This fact is in favour of the electrical origin of hail, as it is well-known to be common in temperate climates, where the air is in a high state of electricity, and to be the frequent concomitant of thunder and lightning. The only substance resembling hail that is generated in the frigid zone consists of a white, porous, spherical concretion of light and snowy texture.
Snow is so very common in the arctic regions, that it may be boldly stated, that in nine days out of ten, in April, May, and June, more or less snow falls. With southerly winds, near the borders of the ice, or in situations where humid air, blowing from the sea, assimilates with a gelid breeze from the ice, the heaviest falls of snow occur. In this case, a depth of two or three inches is sometimes deposited in an hour. The thickest precipitations also frequently precede sudden storms. The form of the particles of snow presents an endless variety. When the temperature of the air is within a degree or two of the freezing point, much snow falls, frequently consisting of large irregular flakes, such as are common in Britain. Sometimes it exhibits small granular, or large rough white concretions; at others, it consists of white spiculæ, or rude stellated crystals. But in severe frosts, though the sky appears perfectly clear, lamellar flakes of snow, of the most regular and beautiful forms, are always seen floating in the air, and sparkling in the sunbeams, and the snow which falls in general is of most elegant texture and appearance.