Arctic Dreams, page 26
The first time I recognized the northern lights was on a flight from Seattle to Anchorage, when I saw them above the Wrangell Mountains. It was a clear night, and at first I thought it was only a long, moonlit orographic cloud, the kind one often sees isolated over a mountain. Then I saw it move. Completely absorbed, I watched the long banner of pale light, unfurling in lateral movements over the snow-white mountains until the plane turned away. The motions were like a t’ai chi exercise: graceful, inward-turning, and protracted.
The bottom of an auroral display rarely comes as close as 100 miles above the earth. To the human eye, however, the thin wall of light sometimes appears actually to touch the earth because of a problem of depth perception with objects of unknown size in space. Accurate descriptions are further complicated by its overwhelming size, and its movement. The light wall is often hundreds of miles long and 150 miles or more high; as the intensity of auroral activity increases, the “curtain” of light begins to undulate in a horizontal direction, folding back on itself in huge S-curves and then unfurling again.
There are additional problems with perspective and scale. To someone underneath the display (the top of the wall is tipped toward the south), the aurora may appear like a convergence of rays toward an apex above. Seen edge-on (from directly beneath the bottom edge), the display may seem like luminous smoke rising from the earth. From a distance it may look like a weightless curtain of silk, hanging straight down and rippling in the night air.
The aurora occurs in a thin corridor called the auroral oval centered on the North Magnetic Pole. The display is created by an electric discharge in the earth’s ionosphere and is apparent to us because some of the energy released is visible light. The most common tinting, of pale, whitish green and pinkish rose, is light emitted from oxygen atoms. During intense periods of auroral activity, nitrogen molecules release a crimson light, usually apparent only at the bottom edge of the auroral curtain.
Imagine that your view is from the sun and that you are facing the earth. To your far left on the earth’s surface are the penumbral shadows of dawn. Before you is the bright light of noon. To your far right the border between evening and night. Streaming outward from the sun is a gas of ionized, or charged, particles, mostly helium and hydrogen nuclei, called the solar wind. These particles pass around the earth as though it were a rock in a stream of water. In doing so they flatten the planet’s magnetic field (the magnetosphere) on the near side (day) and elongate it on the far side (night). As it flows past the earth, the solar wind generates an electric current from left to right. The path of least resistance for the solar particles that carry this current is along force lines in the earth’s magnetic field that curve down to the earth’s surface in the polar regions (like the embrasure of an apple, where the stem is). Particles pouring into the polar regions from a positive terminal on the left create the aurora. As they flow up and out to a negative terminal on the right, they constitute a separate invisible phenomenon, the polar wind.
As the stream of particles flows earthward down the funnel-shaped surface of the magnetosphere at the Pole, it excites electrons in oxygen atoms and nitrogen molecules which, as they settle back into a stable state, emit energy—X rays, infrared and ultraviolet light, radio waves, and visible light.
The still wall of light we perceive curved along an east-west arc is the calmest sort of auroral display. The more energetic the sun’s streaming particles, the deeper they penetrate into the earth’s ionosphere and the taller the wall of light becomes. Varying intensities in the electric field produced by the solar wind, and in the solar wind’s own magnetic field, cause the wall to develop a series of fine corrugations and folds perpendicular to its east-west extension, to surge in several directions, and to break up into patches. The changes in the electric and magnetic fields that produce, respectively, the changes in color and motion are caused by magnetic storms on the sun. Major magnetic storms occur in an eleven-year cycle, in association with solar flares in the vicinity of sunspots and in solar features called coronal holes. Magnetic substorms, far more common, create the sequence of auroral events that arctic viewers think of as “typical” for an arctic winter evening. First, a sudden brightening resolves itself into a transparent auroral curtain. Its fine corruscations (rays) become more prominent. There are surges of movement east and west across the curtain, which starts to develop deep folds. The entire display may then move steadily north. Toward dawn it breaks up into isolated luminous patches, like clouds.
The power produced in this generator is astonishing—1 trillion watts with a current of 1 million amperes. The most violent solar storms affect magnetic compasses, wreak havoc with radio communications and certain navigational systems, and create induced electric currents in long conductors like the trans-Alaska pipeline.
Many people claim the aurora makes a sound, a muffled swish or “a whistling and crackling noise, like the waving of a large flag in a fresh gale of wind,” as the explorer Samuel Hearne wrote. And some Eskimos say “the lights” will respond to a gentle whistling and come nearer. They easily evoke feelings of awe and tenderness; the most remarkable effect they seem to have, however, is to draw a viewer emotionally up and out of himself, because they throw the sky into a third dimension, on such a vast scale, in such a beautiful way, that they make the emotion of self-pity impossible.
I remember flying from Prudhoe Bay to Fairbanks one winter night. The sky was clear and the aurora borealis was very strong. With moonlight from the south the snow-covered landscape below was bright, its relief evident in ground shadows. Even the faint line separating the snow-covered tundra from the snow-covered ice was apparent. The auroral curtain stretched out to the west from my view, toward the village of Wainright and the Chukchi Sea. It was in its early, quiescent form of diaphanous rays, a long, pale ghost fire. I could see the edge of the Brooks Range and the plain of the North Slope below. I recalled days of camping in the mountains, of traveling on the tundra, and the times I’d camped on the arctic coast west of Prudhoe. I could see these places clearly, but it was the aurora, towering over the earth, that resolved what could have been only a map into a real landscape, making the memories seem immediate and tangible.
No one knows whether the first Europeans found their way to Iceland, and thence to Greenland and North America, by accident or by design. A reasonable thought is that Iceland occasionally appeared to people in the Faroe Islands as a great looming mirage, like the one of Somerset Island I saw that day. Such mirages often occur whenever a mass of warm air lies over a body of cold water. Light rays that under other conditions might travel straight off into space are bent, or refracted, back earthward in a series of small steps as they pass through layers of air at different temperatures.
Mirages are usually divided into two categories: in superior mirages, like the one of Somerset, the image the eye sees of an object is a false image above the actual object; in an inferior mirage, the false image occurs below the object. Superior mirages are commonly seen at sea in the Arctic in summer, especially late in the afternoon of a clear day. Distant islands, ships, coastlines, and icebergs lying beyond the real horizon all appear to be closer than they are, the sea itself appears slightly concave, and the horizon seems unusually far off.
Superior images are created when light waves pass from denser (or cooler) air in the lower atmosphere into air that is less dense (or warmer). Evenly spaced layers of successively warmer air (i.e., layers of air arranged in a perfect temperature gradient) work like a series of eyeglass lenses, each of which is successively less corrective. A ray of light passing through them all is bent back earthward in a smooth arc. The viewer sees a single clear image of the real object.
If the lenses are arranged, however, so that a more corrective lens comes between two less corrective lenses, the ray of light is turned back on itself. If it is turned back sufficiently (e.g., because of a strong temperature inversion in the lower atmosphere), a viewer will see not only the primary image but a second, inverted image on top of it. Another series of corrective lenses “out of sequence” (i.e., a second temperature inversion in the lower atmosphere) will create a third image, this one right-side-up on top of the second image. With other changes in the order of the lenses, the primary image itself will disappear entirely, leaving an empty space between the horizon and the second, inverted image.
The degree of “stooping” (the vertical compression common with superior mirages), as well as the number of images that appear, and any apparent magnification of the image, depend on the rate of change of air temperature vertically and the presence of reversals in that rate of change. Mirages, of course, are always imprecise. The distortions come about because of shimmering (due to slight turbulence in the air) and because the entire atmospheric lens itself is astigmatic—it curves more strongly in one direction (vertically) than the other (horizontally). All mirages, therefore, are vertically fuzzy. It is this astigmatic quality of the atmosphere, in combination with complex atmospheric inversions above uniformly bright objects like the sea ice, that gives rise to the most impressive of arctic mirages, the fata morgana. These extensive “mountain ranges” or “urban skylines” seem utterly real to the soberest viewer because of the combined effect of several optical phenomena.
Under mirage conditions, sunlight reflecting off the sea ice, through layers of successively warmer air, in which there is a sequence of slight temperature inversions, creates the appearance of a high grayish rampart in the distance. The wall appears in outline and detail exactly like a distant palisade seen through the earth’s blue haze because the astigmatic atmospheric lens has broken the white ice up into areas of light and shadow, and vertical blurring has eliminated any recognizable features. If the layers of air are then slightly tipped by a breeze and return to the horizontal in a regular rhythmic pattern (which occurs because of gravity), the alternation will produce permanent peaks and spires on an already steady image and the illusion is complete. The upper edge of the mirage appears serrated, like the arête of a mountain range; the gray walls suggest snow-covered slopes, even down to dark ridge lines where wind has apparently blown the snow away; and the clefts of steep montane valleys are apparent.
Mirages were a source of delight and amusement to many arctic travelers. They brought lighthearted feelings and a sense of mock astonishment to the serious, sometimes tedious business of making coastal surveys and plotting a course. Fata morganas stand somewhat outside this tradition of innocent whimsy. Seasoned explorers, vehemently insisting on what they had seen, set down mountains and islands on their charts where there was nothing but empty sky. So convincing were these apparitions that the skepticism of other explorers (or even a member of the same expedition) was met with contempt. Expeditions sent out later to verify these new lands sometimes saw the same fata morgana, further confusing the issue. Only by prolonging their arduous journeys, thereby observing a constant receding of the image, did they prove that the land was not there at all.
So it was for the Macmillan Expedition (1913), sent to confirm the existence of a “Crocker Land,” reported by Robert Peary northwest of Cape Thomas Hubbard, northern Axel Heiberg Island. The “Barnard Mountains,” reported by John Ross in 1818 to extend from Devon Island to Ellesmere Island across Jones Sound, were found not to exist by Edward Inglefield in 1852. American explorer Charles Francis Hall’s “President’s Land” proved an ephemera. The “King Oscar Land” and “Petermann Land” described by an Austrian army officer from Cape Fligeli, Franz Josef Land, in 1884 were never seen again. Vilhjalmur Stefansson set off twice in search of “Keenan Land” in the Beaufort Sea.
Some arctic experts conjecture, especially in Stefansson’s case, that these fata morganas were actually tabular bergs or ice islands. It may, indeed, have been a tabular berg hundreds of square miles in extent that a Cossack explorer named Alexei Markoff found far north of the Yana River delta in 1715. The “prodigious mountains” of ice that blocked his path were never reported again.
The monotonic surfaces of the Arctic create frequent problems with scale and depth perception, especially on overcast days. Arctic hare and willow ptarmigan sometimes disappear against the snow when they are only two or three yards away. Even when a contrasting animal like a caribou or a brown bear is visible on snow or ice, it is sometimes hard to determine whether it is a large animal at a distance or a small animal at close range. In My Life with the Eskimo Stefansson recalls spending an hour stalking a tundra grizzly that turned out to be a marmot. A Swedish explorer had all but completed a written description in his notebook of a craggy headland with two unusually symmetrical valley glaciers, the whole of it a part of a large island, when he discovered what he was looking at was a walrus. Johann Miertsching, traveling with M’Clure aboard the Investigator, wrote of a polar bear that “rose in the air and flew off” as the hunting party approached. A snowy owl. “These comical deceptions,” wrote Miertsching, “are a frequent occurrence.”
The white-out is another familiar deceptive phenomenon. It commonly occurs under an overcast sky or in a fog bank, where light traveling in one direction at a certain angle has the same flux, or strength, as light traveling at any angle in any other direction. There are no shadows. Space has no depth. There is no horizon. On foot you stumble about in missed-stair-step fashion. On a fast-moving snow machine your heart nearly stops when the bottom of the world disappears.
William Scoresby, in his Account of the Arctic Regions (1820), offered an original explanation for mistakes in depth perception that are frequently made along certain arctic coasts. The coasts he had in mind are characterized by an extreme degree of contrast between their barren rock walls and expanses of snow and ice. With no middle tones to work with, the eye has trouble resolving these two-dimensional vistas into three dimensions. The human eye also commonly uses the relative density of blue light scattered in the air to judge distance (this is the light that softens the edge of a far mountain); but the clear arctic atmosphere scatters very little light. Faced with these high-contrast, black-and-white coasts, having no knowledge of their real height, and staring at them through an exceedingly clear atmosphere, early mariners had no idea whether they were 5 or 25 miles offshore. Mogens Heinson, sent out to search for lost colonies in Greenland by Frederick II of Denmark in the sixteenth century, battled ice and snow squalls across the North Atlantic for weeks before he raised Greenland’s southeast coast. With a fresh gale blowing favorably and clear skies, he laid a course for those towering cliffs. After several hours he appeared to be no closer to the coast than when he began. The effect was so convincing that he succumbed to the belief that his ship was being held motionless over an undersea lodestone. Frightened, he put about until the coast of Greenland was far behind, and then set course for Denmark.
It is my habit when I travel to note resemblances, particularly of form and color. For example, that between the bones of a lemming and a strand of staghorn lichen next to it on the tundra. Or the sound of a native drum made from walrus intestine and its uncanny resemblance to the underwater voice of the walrus. Or between, an object I have never seen before and objects I am familiar with—the head of an arctic hare’s rib and the rainspout gorgons of cathedrals. Scoresby’s observation is memorable; a pure contrast of black and white draws much in the Arctic together. Sunlit icebergs on a matte-dark sea are a very common example. But I also remembered this point when looking up to see arctic hares feeding on a shadowed hillside. Or any of the white summer birds against dark hills or soil—ivory gulls and tundra swans. Or the other way around—black guillemots flying over the white ice. Or any of the arctic birds in which the black-and-white pattern is so apparent—snowy owl, snow bunting, dovekie, common loon, snow goose. The black bowhead with its white chin patches. Walrus on an ice floe. Leads in the spring ice.
The startling contrast in these images became a reminder for me of the tendency to register only half of what is there in a harsh land, to ignore the other part, which is either difficult to reach or unsettling to think about. The dim-lit ocean beneath the ice, so difficult of access, remains unknown, as do the winter lives of many of the animals and plants. The ice life of the ribbon seal is known, but not its pelagic life. The beautiful throat-singing of the Eskimo, katajak, is heard by the winter visitor but not the shouts of a shaman bound by his helpers with walrus-hide cord and “traveling” in a trance. Caribou moving through the Ogilvie Mountains like wood smoke in a snowstorm, that image, but not the caribou cow killed by ravens in her birthing.
I would remember a flock of jet-black guillemots, streaking low over the white ice.
In the middle of summer, lying on my back on the warm tundra, I would think about the winter, because the summer by itself was so peaceful and I was trying to understand how the whole landscape fit together. Winter, with its iron indifference, its terrible weight, explained the ecstasy of summer. The effects of winter were disquieting to contemplate. Not the cold, though that could make you whimper with pain; it could, they would say, make rocks give up and shatter. Not the cold but the oppression. The darkness that came down. The winter wind that picked up a boat in a village and pitchpoled it across the frozen beach, as if darkly mad. The oral literature of the Eskimo is full of nightmare images from the winter months, images of grotesque death, of savage beasts, of mutilation and pain. In the feeble light between the drawn-in houses of a winter village, you can hear the breathing of something with ice for a heart.
I remember a January in Fairbanks when the temperature stayed around –45°F for a week. Any bit of moisture in the air turned to crystals, creating an ice fog. It is haunting and beautiful to see the exhalations of a herd of caribou hanging over them like a cloud in that cold, or breath trailing behind a gliding snowy owl. But in Fairbanks, where the fog from furnaces and cars and wood fires was suspended just above the streets, it was oppressive. It blurred the edges of buildings and muffled the sound of the already obscure passing car. Snow as hard as concrete took the curbs away from the streets. In the witless gray light, huge ravens walked the alleys behind stores, tearing at bits of garbage. They hunkered on the tops of telephone poles in the white vapor, staring down, cawing that ear-splitting caw. I never felt anything so prehistoric.
