The following figures illustrate these variations : January JulyPlace. mean. mean. Range.
Cambridge 239 °F.
Utrecht 28'5 Hanover 321 Berlin 31.3 33.2 Posen 29.3 36.2 Warsaw 65.8 39'9 (These places all lie within half a degree of the 52nd parallel, and the altitude in no case exceeds 400 feet.) The following figures indicate the more equable character of the Mediterranean region : January July Place. mean. mean. Ranee.
Murcia Catania 51.4 Athens 48.7 319 Smyrna In January, the coldest month of the year, practically the whole continent lies between the isotherms of F. in the south and F. in the north ; in July, the warmest month, the range of the isotherms is from F. in the south to about 50°F. in the north. The summers are therefore warm in the north and centre of Europe and hot in the south-east and in the Mediterranean region, while the winters are cold all over the continent, except in the countries along the central part of the Atlantic seaboard, where they are cool, and on the Mediterranean, where they are, as a rule, somewhat milder.
Three regions may be recognised in respect to the period of the year in which the greatest amount of precipitation takes place. In the interior of the continent the rainfall occurs chiefly during the summer months, when moisture-bearing winds from the ocean are sucked into the low-pressure area, which at that season of the year lies over the Eurasiatic land mass. On the Atlantic coast lands, however, the heaviest precipitation is in autumn when the sea has lost little of its heat and evaporation is proceeding almost as in summer, but when the land is cooling rapidly and causing condensation to take place. The Mediterranean region, again, has its rainfall in the winter half of the year, when it is under the influence of the westerly winds ; in the summer months the north-east trade wind system gradually extends over it, and the winds, blowing off the land and towards lower, and so warmer, latitudes, are dry.
The regions of heaviest precipitation in Europe are either in the countries which border upon the Atlantic or on the slopes of moun tains which face the rain-bearing winds. Over considerable areas
in these regions there is a mean annual precipitation of 40 inches and more, which decreases in the less exposed districts to between 30 and 40 inches. The greater part of Central Europe has between 20 and 30 inches, but in the north-east and south-east of the continent there is less than 20 inches.
VEGETATION.—The natural vegetative regions of Europe need only be mentioned here, as they have been so greatly altered by the hand of man. In the extreme north there is tundra which soon passes into the poor coniferous forest of high latitudes. About the 60th parallel this coniferous forest begins to merge into the deciduous summer green forest of Central Europe. In the Mediterranean region ever green trees of a sclerophyllous type grow on the lowlands, and deciduous trees on the uplands. The south-east of Russia is steppe land.
Of economic plants barley makes its way furthest north and finds its extreme limit along a line running south-eastwards from about the North Cape to the intersection of the 60th parallel with the European frontier. It is closely followed by oats, but wheat cannot grow beyond the 65th parallel in Norway and Sweden, after which its limit bends to the south-east and enters Russia about the 60th parallel. Rye has a somewhat greater extension, and in Sweden can be grown as far north as the Arctic Circle. The northern limit of maize enters France in the south of Brittany and runs in a north easterly direction as far as the Prussian province of Posen, where it bends to the east, runs through Austria-Hungary by way of Lemberg, and includes Roumania and Southern Russia. The vine has a limit practically the same as that of maize as far as Posen. East of that point the increasing length and severity of winter pushes it to the south of the Carpathians. The area within which the olive is grown is practically coterminous with the region of Mediterranean rainfall.