CLIMATIC IXTLUEXCB OF LAKES, ETC.] 



METEOROLOGY. 



nor 



other hand, the Arctic and Antarctic oceans tend to 

 diminish the temperature of the land, not only in their 

 immediate neighbourhood, but even for many degrees 

 beyond their limits. Siberia, in North Asia ; Lapland, 

 Russia, and Norway in Europe ; Greenland, and British 

 and Russian America, are, to a great extent, frozen and 

 inhospitable climes, owiiig to the extreme cold induced 

 by the Frozen Ocean of the Arctic zone. From the 

 Antarctic circle, northwards, to Patagonia, Tasmania, 

 and New Zealand, the Southern Ocean reduces the mean 

 temperature to an even greater extent than does the 

 northern one in corresponding latitudes, owing, chiefly, 

 to the greater area which is unoccupied by land, and 

 hence not under the influence of the surface-absorption 

 of the solar rays of heat. The difference of temperature 

 between the two oceans is very remarkable ; for we find, 

 that whilst the Arctic has a heat of 40, in lat. 70 N., 

 the Antarctic, in lat. 68$ S., has one of but 30-8 ; the 

 difference for corresponding latitudes, within certain 

 limits, being generally about 10. 



The area of inland seas and lakes is small, when 

 compared with that of the oceans ; but being mostly 

 found in regions far removed from the sea, it must 

 have a decided local effect on the country surrounding 

 their shores. In Europe ; the Baltic, Black, and Medi- 

 terranean seas ; the Russian and Swiss lakes, <tc. in 

 Asia ; the Caspian, Aral, Baikal, and Black seas, Arc. 

 in Africa ; the Red Sea, Lakes Tchad, Nyassa, *c. and, 

 in America, the extensive system of lakes intersecting 

 Canada, the United States, &c. all have a direct 

 influence on the adjacent country, either in reducing or 

 raising its average temperature.* That areas of enclosed 

 water should have these two opposite effects, in the 

 same localities, at different seasons, may at first sight 

 appear anomalous ; but it can be easily explained. In 

 the case of any lake or nearly enclosed sea the Caspian 

 being of the former, and the Black Sea of the latter 

 type it is plain that, during summer, the surrounding 

 lands, owing to the absorption of solar heat, will be 

 of a higher temperature than the waters of the lake, 

 which reflect, but barely absorb, heat. On the contrary, 

 during the winter, tliu water will be warmer than the 

 land, because whilst the latter radiates, and therefore 

 loses its heat acquired during summer, the lake radiates 

 very slowly, and therefore as slowly loses its acquired 

 temperature. Inland seas and lakes thus tend to 

 equalise the amount of heat, and, like the fly-wheel in 

 Mechanics, whilst they add no force, they regulate its 

 distribution. As winter, however, passes away, the 

 surface of unch as are frozen will tend to maintain a low 

 temperature in the surrounding atmosphere, just as we 

 find in the great area of the North Atlantic, the icebergs, 

 floating southwards, lower the temperature of the atmo- 

 sphere ; and coining into contact with the warmer air, 

 in part produce fogs, so common about the banks of 

 Newfoundland, f 



The islands, spread throughout the oceans and seas, 

 must have an effect analogous to that which we have 

 described in respect to the lakes ; and for the reasons 

 already assigned, so far as the absorbing and radiating 

 power of dry land is concerned. It is true that, indi- 

 vidually, like the lakes, <tc., they are extremely small, 

 when compared with continents ; but their great number, 

 especially in the Pacific, compensates for their trifling 

 area. They form so many surfaces from which currents 

 f hot air are continually ascending, that are replaced 

 by constant in-draughts of the cool sea-air. Hence 

 islands generally possess those delightful land and sea- 

 breezes, which, beneath the tropics, are often the only 

 modifying agents that would permit many such places to 

 be inhabited. In the Section on Heat this subject has 

 been fully discussed, and some interesting observations, 

 by Captain Maury, are also quoted, fully illustrating the ' 

 nature of these land and water aerial currents. 



In some islands the opposite coasts possess an entirely 

 different climate a circumstance which is generally 



See, bo, mnuk* on the temperature near the Lake of G triers j 

 <. p. IIM. 

 + The (olio plate*, t pafe 11M, gire the extent of the chief Ukct In 



! attributable to extensive mountain ranges, having a 

 I considerable height above the sea-level ; or to the setting- 

 in of atmospheric currents from the ocean. Iceland 

 presents a remarkable instance of this kind, owing to 

 the different temperatures of the water by which it 

 is surrounded. On the south side the Gulf-stream 

 impinges, and has so great a heating effect, that the 

 average annual temperature is 40 an amount equal to 

 that of Philadelphia, which is in a latitude of nearly 25 r 

 nearer the equator. But on the north side, where no 

 such warming influences prevail, and at a distance of 

 from 100 to 200 miles from the south coast, a region of 

 perpetual snow and ice is found, which, when a north 

 wind blows, often blasts, by its chilling influences, the 

 remainder of the island, and even drives away the fish 

 that otherwise abound iu the surrounding ocean. 

 England, Scotland, Denmark, and Norway, are similarly 

 affected from the same cause ; for on the west coast of 

 each the climate is generally moist and mild ; but the 

 eastern side of each country, being exposed to the dry cold 

 winds arriving from the interior of Russia, is generally 

 bleak, and, in the northern districts, very cold and dry.J 

 The Canaries afford a remarkable instance of this kind. 

 Situated off the west coast of the African continent, and 

 a little to the north of a line passing through the Sahara 

 desert, they experience, at most times, a healthy clim.-ttc ; 

 are refreshed by the sea-breezes, and possess a highly 

 fertile and productive soil. When, however, an easterly 

 or south-easterly wind prevails, the hot and dry winds 

 from the desert reach the islands, accompanied at times 

 with swarms of locusts ; and from these causes, in con- 

 joined operation, every vestige of vegetation is destroyed, 

 the earth is parched up, and a desert, arid waste replaces 

 the former luxuriant verdure. Ceylon presents instances 

 of a similar kind ; but in that island the variations are 

 chiefly due to the differences of eluvatiou of its various 

 parts ; and the mountain chain running thrmi /h the 

 island, has a remarkable effect on the climate of the east 

 and west sides. When the S.W. monsoon sets in, the 

 west side will receive copious rains, and be covered with 

 a luxuriant tropical growth ; whilst, on the east side, a 

 great scarcity of water will be felt, and even an aim st 

 complete suspension of vegetable growth occurs, because 

 the suspended aqueous moisture, arriving with the mon 

 soon, is arrested in its course by the hills, and confined 

 entirely to the opposite side of the island. We believe 

 that similar circumstances affect the climate of Mada- 

 gascar ; but its interior is but little known, and, therefore, 

 no accurate data have been obtained. Borneo has an 

 almost south- European climate on its north side ; whilst, 

 on the south, that of a tropical character subsists. In 

 the Mediterranean, Sicily presents another illustration ; 

 the mean annual temperature of Palermo, on the north, 

 being 6 less than that of Catania on the south-east, tho 

 difference of latitude being only about one degree. In 

 the West Indies, Guadeloupe has a low and hot west 

 coast ; whilst the east, which is elevated, is much more 

 temperate ; yet they are but a few miles apart. The 

 same observations may also be applied to Jamaica, and 

 many of the adjacent islands ; and, generally speaking, 

 each possesses a mountain range or tract, which, as we 

 have already remarked, has so powerful an influence 

 in tempering the excessive heat common to all tropical 

 countries. 



Wo have thus pointed out the chief causes, both of a 

 general and special nature, which often affect the climate 

 of continents, oceans, &c. ; and our remarks will serve 

 as an introduction to a table, in which we have included 

 a variety of facts, carefully selected from various sources, 

 and relating to subjects which have been discussed in 

 the last few pages. The names of tho chief countries, 

 cities, &c., in each division of the world, are given in the 

 first column ; and, when important, several parts of the 

 same country are named, so as to show the results of 

 local disturbing causes. Wherever possible, and when 

 the results could be relied on, tho annual average 



etch hemliphere, and of the inland* In the oeeani ; from which an idea of 

 their influence, wiih rrapect to climate, may be gathered, 

 t See ante, pp. 1177 and 1193. I Sec end of this Section. 



