Page images

crosses the boundary line in latitude 65°. It reaches its most northern point just on the Arctic Circle, in longitude 146°, .and thence flows southwestward to its mouth. It is navigable for small steamers throughout its course in Alaska, and when not closed by ice-that is, from June to October-carries much traffic, since nearly all of the food, supplies, machinery, and other goods for the support of the mines in Alaska and the Klondike come by this route.

North of the Yukon most of the land is permanently frozen at a depth, thawing only near the surface in summer. Whenever the slopes are at all gentle such ground is marshy, forming the well-known tundra of the Arctic regions.


We must speak of the climates rather than the climate of Alaska, for different

parts of the Territory differ in climate, not in degree only, but in kind. The Pacific coast has a climate of its own, the coast of Bering Sea has another, and both differ widely from that of the interior.

The climate of the Pacific coast, from Portland Canal in the extreme southeast to Attu Island at the west end of the Aleutian chain, may be characterized, in a word, as "chilly." Take the wellknown climate of San Francisco, with its dampness, fogs, and cold sea winds, reduce the temperature 15 to 18 degrees and increase the dampness and fog in proportion, and you have a fair idea of the climate of the Alaska Pacific coast. At Sitka, in latitude 57°, the mean annual temperature is 43° Fahrenheit, which is about the same as at Eastport, Maine, 12 degrees farther south. The extreme range of temperature on record

[graphic][subsumed][merged small][merged small]
[graphic][subsumed][merged small][merged small]

at Sitka is from a trifle below zero Fahrenheit to 90° above, and the monthly mean temperatures range from 31° to 56° only, illustrating the wonderfully uniform temperature of the Pacific coast. At Kadiak, 16 degrees farther west and a degree farther north, the mean temperature is 2° lower and the extreme range of temperature less. At Unalaska, 3 degrees south of Sitka, the mean temperature is only 36° and the range of temperature is still smaller.

While the mean annual temperature on this coast, whose latitude ranges from 54° to 60°, does not differ materially from that of Eastport, Maine, on the Atlantic coast, in latitude 45°, the summer temperature is much colder and the winter temperature much warmer. The statement has been made that it is

no colder at Sitka than in Georgia. I believe this to be true in the sense that the minimum temperature is no lower; but it represents only a part of the facts, and much the less important part. It is also true that it is no warmer at Sitka than in Greenland or Labrador-that is, the maximum temperature is no greater; and for most economic purposes, except the making of ice, it is warmth, not cold, that concerns us.

The annual rainfall is heavy over this entire coast. At Sitka it is more than double that of the Atlantic coast, 105 inches a year being the record, and it diminishes but little westward. At Unalaska the record is 92 inches. Rain falls mainly in the autumn and winter, the summer being comparatively dry.

A description of climate would be in

[graphic][merged small]

complete if it did not include the amount of sunshine and cloudiness, since these are important factors in the growth of plant life. At Sitka it is cloudy twothirds of the time, and nearly half of the time it is raining or snowing. At Kadiak the conditions are a little better; at Unalaska they are worse, for Unalaska is unrivaled for bad weather. Only 8 days in the year during several years of record were entirely clear and only 45 partly clear, the remaining 312 being cloudy, and 271 of those were rainy or


Before attempting to explain these peculiarities of climate, it should be stated that the sea commonly produces two modifications of temperature. It may reduce the extremes, making the atmosphere cooler in summer and warmer in winter, and it may reduce or increase the mean annual temperature. The Pacific coast of Alaska is within the range of the prevailing westerly winds of the northern hemisphere. These winds come off the ocean, bringing to the coast the temperature of the sea. As the sea absorbs heat slowly, in comparison with the land, and parts with it as slowly, the winds blowing off it are cool in summer and warm in winter. Moreover, since the ocean has waves, tides, and currents, by which its waters are moved about, the cold water of the north toward the south and the heated water of the tropics toward the north, there is a tendency to establish an equilibrium of temperature. Thus the northern seas are warmer, on the whole—that is, the mean annual temperature is higherthan land in the same latitudes, and through the agency of the westerly winds the coast shares in this amelioration of temperature.

These same westerly winds are responsible for another feature of the climate, the heavy rainfall. They come from the sea saturated with moisture, and if they find the land colder than they are, as it is in fall and winter, they are chilled below the point of saturation and disgorge copiously; but if they find

Photo by Curtis

An Indian Totem

[graphic][subsumed][merged small][merged small]

the land warm, as it is in summer, they carry their moisture inland and the coast enjoys a comparatively dry season. This season is, however, dry only in comparison with the winter, the wet season. The rainfall of the three winter months at Sitka is commonly about 30 inches, while that of the three summer months is 16 inches, or more than half that of winter.

The fogs of this coast, really the most obtrusive feature of the climate, occur whenever the wind blows from the sea, which it does most of the time, even in summer. For obvious reasons they seldom or never occur with a land breeze.

The coast of Bering Sea has a climate widely different from that of the Pacific coast. The mean annual temperature is much lower, even after due allowance for the difference in latitude. At St. Michael it is 26°, and at Port Clarence, in Bering Strait, it is 20°. The range of temperature is much greater. The mean temperature of the coldest month at St. Michael is 2°, of the warmest month 54°, showing a range of 56°.

[ocr errors]

Similarly, at Port Clarence the coldest month is 11°, the warmest 50°, a range of 61°. The highest temperature on record at St. Michael is 75°, the lowest - 55°, a range of 130°. The contrast with the Pacific coast is still greater in the matter of rainfall, which at St. Michael is very light, amounting to only 14 inches annually. Moreover, rain falls in the warm rather than in the cold season.

The temperature of this coast is not much modified by the sea. Bering Sea is practically a closed sea, the Aleutian Islands forming a partial barrier against the warmer waters of the Pacific; consequently its waters retain, to a large extent at least, the temperature incident to the latitude. Its mean annual temperature is little affected by outside influences, and the greater part of it is frozen for half the year. The extremes of temperature, however, are reduced by the slow absorption and radiation of heat, just as with the Pacific. As this region is north of the territory of the prevailing westerlies, the winds have no preva

« PreviousContinue »