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Zone 3, No. 3. Port Refuge
3, 1. Northumberland Sound
4. Melville Island
4. Dealy Island .
9. S. E. Boothia Felix
il, Port Bowen
15 10 28 18 6 9 6 15 5 1 4 38 29 13 5 6
4 28 3 11 13 12 7 21 7 20 3 20 6 10 4 30 28 5 4 11 13 7 20 12 46 0.3 13 6 6 1 8 19 22 14 2 6 9 15 11 22 38 7 11 6 6 3 5 24 26 15 5 4 11 10 12 16 29 6 4 6 17 12 6 21
4 25 8 3.5 1.8 5.5 14 38 2.4 16 00.30.1 2 12 67 2.6 21 6 0.4 0.5 4.5 12 53 2.4 15 00.10.11.6 13 68 16 11 15 8 6 11 18 16 | 12 7 61 7 01.2 3 9 22 7 6 21 4 5 9 26 26 8 4 2. 2. 2 16 39 16 8 8 10 12 9 13 23 27 3 2 50.6 2 8 52 18 14 14 10 9 14 8 13 19 7 12 18 9 8 11 16 15 7 6 7 6 5 21 33
The prevalence of the N. and N. W. winds is here strongly marked, especially in winter. At two of the stations more than half of all the winds come from the N.W. The exception presented by Port Bowen, where E. winds largely prevail in winter, is explained by the large land-mass to the E. The winds of the inland and western stations of Arctic America, as well as the Arctic Ocean in their vicinity, show more irregularities.
Zone 6, No. 8. Fort Simpson
6, " 7. Fort Norman “ 6, Nos. 10, 11. Forts Enterprise and Reliance " 5, No. 5. Fort Franklin " 5, " 4. Fort Anderson
6, 3. Fort St. Michael's, Alaska " 6, " 5. Ikogmut, Alaska “ 6, Bebring's Strait, 1720-1600 W. "65,
177° E.-1600 W. 66 4, W. Arctic Ocean, 1550-175° W. " 7, No. 16. York Factory .
7, 17. Little Whale River
7 2 27 6 1 101
2 44 8 0.7 17 17 2 4 1735
0 24 23
11 23 18 2 5 17 16 7. 0 9 42 21 0.9 2 6 18 2 13 20 7 1.2 2 14 42 37 6 9 4 18 5 16 4 29 6 15 5 15 8 15 7 27 4 6 2 28 16 12 425 17 7 15 19 13 1.5 3 11 19 9 4 4 22 14 17 10 25 12 7 15 10 7) 13 12 15 10 13 21 16 7 6 15 8 9 12 20 8 12 17 24 25
7 6 8 10 7 13 15 28 23 5 18 2 3 5 20 4 11 4 25 13 12 12 28 7 6 10 2 28 9 10 3 3) 11 19 22 15 19 2
From the foregoing table it appears that in Northern British America (Forts Norman, Simpson, Enterprise, Reliance, Franklin, and Anderson) there is no accordance in the direction of the winds. They seem to vary much according to locality. This is a very cold region, and being continental, calms are much more prevalent in winter than in the Archipelago. We must expect to find here higher pressure in winter than further to the east, because the depression about Iceland is not so near.
The great distance of the Atlantic depression and the mountains which lie between this region and the Pacific depression, also explain the undecided character of the winds in winter.
We have fewer observations in the summer. Among these, Fort Franklin has prevailing E. winds, coming from Great Bear Lake, where the ice does not melt till the end of the summer.
In Alaska monsoon winds are seen to prevail from the N. E. (the land) in winter,
S. W. in summer. In Behring Strait southerly winds are also more numerous in summer, while the Arctic Ocean northward of it has northerly winds at the same
In the last two stations lying near Hudson's Bay, a monsoon influence is exhibited in the S. winds of winter. Hudson's Bay does not freeze entirely, and thus the wind will blow towards it from the land. (See Maps, Plates 5, 6, and 14.)
TEMPERATE ZONE OF AMERICA WEST OF THE ROCKY MOUNTAINS.
On the coast of Alaska and further south in Washington Territory, the winds have a monsoon character. The cause of this is the difference of temperature and consequently of pressure on land and sea, producing a current of air from the land in winter, and from the sea in summer.
It is necessary to remember that the warm current of the Kuro-Sivo, the Gulf Stream of the Pacific, passes, in its return to the south, near to this coast, and there must be a diminished pressure over the region, at least in the colder part of the year. The interior of the continent is very cold at that time, and therefore the pressure of the air must be high there.
In the summer there is a narrow cold current passing between the coast and the Kuro-Sivo, while at the same time the interior of the continent has a great excess of temperature over the coast, and, as in other dry and warm continental areas, the pressure must be low.
There is no country of the world where the temperature of the summer increases so much as we go from the coast to the interior as on the Pacific slope of America, from Alaska to Lower California. The summer isotherm of 59° passes near San Francisco on the coast of California, and is supposed to reach the polar circle on the Yukon River, in the interior of Alaska, a difference of 28° in latitude. Fort Miller, in the interior of California, has a summer temperature of 850,5, and Monterey, on the coast, and in the same latitude, but 59.0; difference 26.5 F. The percentage of winds in Alaska and Washington is given below, and, with the help of the maps, Pl. 5 and 6, will serve to illustrate the winds of this region. Plate 14 gives the atmospheric pressure.
If, as was said before, the winds of this coast have monsoon features, these monsoon winds do not overpower others, especially in winter. At that season of the year the pressure is high in the latitude from 250 to 35° N. on the coast of California, and in the same latitudes on the Pacific Ocean. Winds from this region are quite frequent, and passing over the warm waters of the Japanese current, give a very warm climate to the whole coast. The winter temperature of Sitka is equal to that of New York, and above that of St. Louis.
It seems to me that the S. E. winds which are so frequent on this coast, are, partly at least, the deflected S. W. winds of the Pacific. The mountain-chains give them a direction from the S. S. E.
The Aleutian islands are very near to the centre of lowest pressure on the Pacific, at least in winter. They occupy a position similar to that of Iceland in the Atlantic; the same may be said of the island of St. Paul in Behring Sea. The storms are frequent and severe, and the winds polar and equatorial in turn, without a marked predominance of either. In summer the centre of depression moves to the northward and inland, and accordingly the winds are principally from the south.
In Washington Territory the winds of the coast-region are very similar to those of Sitka. In the interior of Washington and Oregon the winds have no strongly marked monsoon character. (See also Maps, Pl. 5, 6, 8, and 11.)
The S. W. is here the prevailing wind, winter and summer, as in the same latitudes on the oceans and in Europe. We must see in these winds a continuation of the equatorial current of the Pacific, which crosses the coast-ranges and descends into the valleys, while part of it is deflected by these mountains and appears as a S. E. wind at Sitka. The winds of California differ in some respects from those of the northern Pacific coast. They are westerly at all seasons of the year, more S. W. in winter and N. W. in summer. The winds of the summer are very strong and steady, giving to the California coast a peculiar climate-a summer colder than anywhere in the same latitude even in the southern hemisphere. In some places the prevailing winds in summer are S. W., and the mean direction also south of W. This is probably due to the position of the coast, so that the S. W. seems to be a local sea-wind. At San Diego the number of miles was also observed, and I have calculated separately the percentages for the number of observations and for the number of miles, in the three summer months.
Thus the N. W. wind largely prevails if the number of miles is taken into account. The following is the percentage of winds in California, Oregon, and Nevada.
The mean direction of the wind in the four seasons is as follows in the same western region of North America.
Thus in summer, westerly winds very largely prevail in this region, while in winter the ratio of resultant is much smaller in California and Oregon, and easterly winds prevail further north, as shown also by the map, Plate 8.
The geographical features of the North American continent are such as to exclude a great part of it from the influence of the Pacific Ocean. The mountainchains are higher in the west than in the east, and, what is more important still, there is a very extensive plateau occupying nearly all the western half of the continent, between 34° and 42° N. L. The eastern part of this plateau, in eastern Wyoming, Colorado, and New Mexico, and in northwestern Texas slopes gradually towards the east—the valley of the Mississippi—and is thus subjected to the influence of the Gulf of Mexico. This influence is especially felt in summer,
when the heated and rarefied air of the plains draws in that of the surrounding regions.
On the west these plateaus are walled in by ranges of mountains, and the indraught of air from the Pacific slope is thus prevented.
We know that there is a depression of the barometer in summer over the plateaus of the interior, but there are yet too few observations to decide as to the region where this depression is greatest. It is, however, most probable that it is in Utah.
There is also a low region, where pressure must be low in summer, that is the valley of the Gila and lower Colorado. The heat is extreme there, Fort Yuma and vicinity having the warmest summer in America, and the ascending current must be very powerful. Air is drawn in towards this hot region, and, owing to its geographical position, principally from the south, from the Gulf of California. (See also Map of Isobars, Pl. 14, and of Winds, Pl. 8 and 11.)
The following table gives the percentage of winds of the region east of the coast;
The predominance of southerly winds in summer, as shown by this table, is very great, and it must be remembered that the greatest part of this region is mountainous, and thence great local discrepancies should be expected. The period of observation was short in nearly all cases. Considering this, the agreement between the different regions is very satisfactory. (See Plates 8 and 11.) In Utah there are less southerly winds in summer, and still less in Montana. But this is easily explained. As Montana lies north of 44° N. latitude where there is no xtensive plateau, and the mean height of the Rocky Mountains is less than to the south—the westerly winds from the Pacific can therefore readily reach Montana.
We should also expect to see southwesterly winds in winter in Montana, as in California and Oregon. This is really the case. In Arizona and New Mexico, on the contrary, the winds are much more northerly in winter than in summer. I give below the mean direction of the wind in some of the regions here considered. (See also maps, Plates 5, 6, 8, and 11).