The appearance of the Greenland atmosphere corresponds in some degree with the winter sky of Britain; the colour of the former is, however, of a deeper azure, and its transparency, when clear and free from icy crystals, perhaps more perfect.
Far within the borders of compact ice the atmosphere, in summer, is often cloudless, and the weather serenely pleasant, though cold. But in the usual fishing-stations, and on the exterior of the ice in general, a clear sky is not frequent; nevertheless, when it does occur, its transparency is peculiarly beautiful. The sun sometimes sweeps two or three times round the Pole, without being for a moment obscured by a cloud. Objects the most remote may be seen perfectly distinct and clear. A ship’s top-gallant-mast, at the distance of five or six leagues, may be discerned when just appearing above the horizon, with a common perspective glass; and the summits of some mountains are visible at the distance of sixty to a hundred miles. This perfect clearness occurs most frequently before easterly winds; in general, however, especially in very cold weather, objects on the horizon, when viewed with a high magnifier, appear affected with a perpetual tremor; whence the contemplation of distant objects is accomplished as perfectly with a good pocket-glass as with the best telescope. This tremulous motion is evidently produced by the quantity of delicate icy crystals which, in very low temperatures, are almost always seen floating in the air.
The general obscurity of the atmosphere, arising from clouds or fogs, is such, that the sun is frequently invisible during several successive days. At such times, when the sun is near the northern tropic, there is scarcely any sensible variation in the quantity of light from noon to midnight. Hence, when the sailors have been long abroad in the boats, or so fully engaged as to be unable to mark the progress of time, the inquiry, whether it be day or night, is not unfrequent.
There is nothing remarkable in the appearance of the sun at midnight, excepting that, when its altitude is very small, it may be viewed with the naked eye, without producing any painful sensation; but when it is more than four or five degrees above the horizon, it generally appears as effulgent as with the same elevation in Britain. The force of the sun’s rays is sometimes remarkable. Where they fall upon the snow-clad surface of the ice or land, they are, in a great measure, reflected, without producing any material elevation of temperature; but when they impinge on the black exterior of a ship, the pitch on one side occasionally becomes fluid, while ice is rapidly generated on the other; or, while a thermometer, placed against the black paint-work on which the sun shines, indicates a temperature of 80° or 90°, or even more, on the opposite side of the ship a cold of 20° is sometimes found to prevail.
This remarkable force of the sun’s rays is accompanied with a corresponding intensity of light. A person placed in the centre of a field or other compact body of ice, under a cloudless atmosphere and elevated sun, experiences such an extraordinary intensity of light, that if it be encountered for any length of time, is not only productive of a most painful sensation in the eyes, but sometimes of temporary, or even, as I have heard, of permanent blindness. Under such circumstances, the use of green glasses affords a most agreeable relief. Some of the Indians of North America defend their eyes by the use of a kind of wooden spectacles, having, instead of glasses, a narrow perpendicular slit opposite to each eye. This simple contrivance, which intercepts, perhaps, nine-tenths of the light that would reach a naked eye, prevents any painful consequences in the most intense reflection of light that ever occurs.
The constant light of the sun during the summer prevents the stars from being seen; and this, together with the frequency of cloudy or foggy weather, rarely admits a sight of the moon. Hence, the longitude, which is of such essential importance in navigation, can seldom be determined by lunar observations. Chronometers, therefore, though but little used by the whale-fishers, become of enhanced value; and even a good watch, well regulated, will, where the degrees of longitude are so very contracted, point out the meridianal situation of the ship for short intervals, with a very tolerable degree of accuracy.
Though the air in the arctic seas is generally in a state of dampness, approaching to complete saturation, yet the absolute quantity of moisture cannot, when the cold is very excessive, be considerable. It is remarked, that vessels are less apt to rust here than in any other climate; and this observation, if we consider the relative humidity of the atmosphere as indicated by the hygrometer, is certainly correct; but though the air in the Polar regions is generally damp, yet it is probable there is no habitable situation in the known world in which such a degree of actual dryness prevails, as in a house or in the cabin of a ship, well heated, when the external air is intensely cold. The wainscoting of the cabin of a ship in cold weather sometimes shrinks, in consequence of the uncommon dryness, as much as half an inch in a panel of about fifteen inches broad, being equal to one-thirtieth of the breadth; but, on returning to Britain, the same panel expands again to almost its original dimensions.
Few observations, comparatively, seem to have been made on the electricity of the atmosphere, especially in high latitudes. Perhaps, some trials that I made in the spring of 1818, on this subject, were the first that have been attempted within the arctic circle. When in latitude 68°, I erected an insulated conductor, eight feet above the maintop-gallant mast-head, connected by a copper wire with a copper ball, attached by a silk string to the deck. The conductor consisted of a slender tapering tube of tinned iron, terminated by a pointed brass wire. It was fixed in an iron socket, supported by a large cylindrical piece of glass; which glass, by means of another iron socket, was secured to the top of a long pole, elevated several feet above the mast-head. A tin cone encompassed the bottom of the conductor, the mouth of which being downward, defended the rod of glass from getting wet, so as to injure its insulated property. The conducting wire, being kept clear of the rigging of the ship, was expected to exhibit in the ball, where it terminated, any difference between the state of the electricity of the ship or sea and that of the atmosphere. The test of electricity was a Bennet’s gold-leaf electrometer, brought into contact with the ball; but though trials were made for several successive days, from lat. 78° to lat. 75°, during clear, cloudy, and showery weather, not the least excitation was ever observed. That the effect might be rendered more perceptible, the electrometer was well dried and warmed immediately before each experiment, without which, indeed, no excitation could be produced in it, either with glass or sealing-wax. The nights being light, the aurora borealis could not be seen; but on the evening of the 20th of May, an appearance was observed, very much resembling the aurora borealis, yet no signs of electricity were observed in the electrometer applied to the conductor.
There are several phenomena of the atmosphere dependent on reflection and refraction, deserving of notice. Ice-blinks have been already mentioned, when speaking of the ice. Under certain circumstances, all objects seen on the horizon seem to be lifted above it a distance of two to four, or more, minutes of altitude, or so far extended in height above their natural dimensions. Ice, land, ships, boats, and other objects, when thus enlarged and elevated, are said to loom. The lower part of looming objects are sometimes connected with the sensible horizon by an apparent fibrous or columnar extension of their parts, which columns are always perpendicular to the horizon; at other times, they appear to be quite lifted into the air, a void space being seen between them and the horizon. This phenomenon is observed most frequently on, or before, an easterly wind, and is generally considered as indicative of such.
A most extraordinary appearance of the Foreland, or Charles’s Island, Spitzbergen, occurred on the 16th of July, 1814. While sailing to the southward, along the coast, with an easterly wind, I observed what appeared to be a mountain, in the form of a slender, but elevated, monument. I was surprised that I had never seen it before, and was more astonished when I saw, not far distant, a prodigious and perfect arch thrown across a valley, of above a league in breadth. The neighbouring mountains disclosed the cause, by exhibiting an unnatural elevation with the columnar structure of looming objects. Presently, the scene was changed, the mountains along the whole coast assumed the most fantastical forms; the appearance of castles, with lofty spires, towers, and battlements, would, in a few minutes, be converted into a vast arch or romantic bridge. These varied, and sometimes beautiful, metamorphoses naturally suggested the reality of fairy descriptions; for the air was perfectly transparent; the contrast of snow and rocks was quite distinct; even in the substance of the most uncommon phantasms, though examined with a powerful telescope, and every object deemed to possess every possible stability. I never before observed a phenomenon so varied or so amusing. The land was not alone affected by this peculiar refraction, since every object between the north-east and south-east points of the compass was, more or less, deformed by it. A mass of ice on the horizon appeared of the height of a cliff, and the prismatic structure of its front suggested the idea of basaltic columns. It may be remarked, that these phenomena took place on a clear evening, after an uncommonly warm afternoon.