Page:The American Cyclopædia (1879) Volume IV.djvu/694

 682 CLIMATE entire valley of the Mississippi, there is a novel change apparent in going westward to the foot of the Kocky mountains, the degree of heat in- creasing not only relatively but positively, being greater at considerable altitudes of the great central plateaus than on the Atlantic coast in the same latitudes. Thus at Fort Benton, Virginia City, Laramie, and Denver, points at various altitudes from 2,500 to 6,000 ft. above the sea, at the eastern foot of the Rocky moun- tains, the climate is milder than at sea level on the Atlantic coast in the same latitudes. At Fort Benton, on the upper Missouri, lat. 47 50', and 2,700 ft. above the sea, the mean is 10 warmer than at St. John's, Newfoundland, nearly in the same latitude. At Fort Laramie, 4,500 ft. above the sea, it is warmer by 2 or 3 in the annual mean than at Boston, nearly in the same latitude. Denver, at 6,000 ft. above the sea, is as warm as Baltimore, which is in the same latitude. These are representa- tive positions for a large mass of interior sur- face, on which the climate is in marked con- trast with the usual standards for like eleva- tions, and where also the special modifying in- fluences of the Pacific do not reach. A like anomaly exists on the great plateaus of central Asia, which has been noticed by Humboldt, and was recognized by him as establishing a new form of continental influence, or that of increased heat due to the presence of great elevated areas. Again, of new and striking developments in the climates of the western coast of North America, there are illustrations in the abrupt contrasts of the immediate coast of the Pacific with the interior, especially in summer. The peculiar cold winds of that coast in summer are met with off the coast before reaching the 30th parallel, and they are severe and almost violent from lat. 35 to 45 N., or almost to the mouth of the Columbia. They are due, as has been stated, to the vast mass of cold water moving from the northwest as a deep-sea current, and rising to the surface on the immediate coast. The highly heated plains and basins of the interior cause great rarefaction of the air in those basins, toward which the colder mass of the coast is drawn with force during the day, to subside in calm at night when radiation has cooled the tem- perature and restored the equilibrium. Fur- ther north the sea is warmer, both positively and relatively, and no contrast exists with the temperature of the land. The summer is very warm, and the climate most prolific in both animal and vegetable life over all Alaska and the broad valley of the Yukon, to lat. 65 or 68 N. Here again are marked contrasts of the Yukon and Mackenzie river valleys with the great plains eastward to Hudson bay. On this tract, and still more eastward and north- ward of this bay, the maximum of continental refrigeration exists, and a summer is scarcely known. The extreme severity of the climate of this district, down to the lower border of Labrador, is in marked contrast with the cli- mate of like areas of Asia, rendering it less ca- pable of occupation than any other area of the earth's surface. At Fort Hope, Repulse bay, there are but two months, July and August, in which the mean temperature is above freez- ing ; while at Yakutsk, East Siberia, in nearly the same latitude, there are five months with the mean above freezing, and the summer mean is 58'5, compared with 39'7 at Repulse bay. In the northeast of Ireland, says Humboldt, lying under the same parallel of latitude as Konigsberg in Prussia, the myrtle blooms as luxuriantly as in Portugal. The mean temper- ature of the month of August, which in Hun- gary rises to 70, scarcely reaches 61 at Dub- lin, which is situated in the isothermal line of 49 ; the mean winter temperature, which falls to about 28 at Pesth, is 40 in Dublin (whose mean annual temperature is not more than 49), 3-6 higher than that of Milan, Pavia, Padua, and the whole of Lombardy, where the mean annual temperature is upward of half a degree further south than Stockholm, the winter temperature is 39, and conse- quently higher than that of Paris, and nearly as high as that of London. Even in the Faroe islands, at latitude 62, the inland wa- ters never freeze, owing to the favorable in- fluence of the west winds and of the sea. On the charming coast of Devonshire, near Sal- combe bay, which has been termed on account of the mildness of its climate the Montpellier of the north, the agave Americana has been seen to blossom in the open air, while orange trees trained against espaliers, and only slightly protected by matting, are found to bear fruit. There, as well as at Penzance and Gosport, and at Cherbourg on the coast of Normandy, the mean winter temperature exceeds 42, fall- ing short by only 2'4 of the mean winter tem- perature of Montpellier and Florence. In com- parison with the western coast of Europe, it is believed that the western coast of America is somewhat colder, although more equabte than the eastern part of the western continent. A. Keith Johnston says : " The climates of the Asiatic coast correspond with those of America along the Atlantic; and those of Columbia, Vancouver, and Washington are duplicates of those of western Europe and the British islands. The climate of California resembles that of Spain ; the sandy plains and rainless region of Lower California reminding one of Africa with its deserts between the same parallels." " The elastic atmosphere and bracing effect of the Pacific climates," says Blodget, " constitute a striking difference from those of the eastern states. All residents concur in pronouncing it more favorable to physical and mental activity than any they have known." ("Climatology of the United States," p. 200.) According to observations made at West Point, N. Y., and Fort Trumbull, Conn., both in lat. 41 22', and but 1| of longitude apart, the winters are 4'67 milder and the summers 1 cooler at
 * 55. At Stromness in the Orkneys, scarcely