Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/636

 (29.37 inches) west of Iceland, and another not quite so low in the Barents Sea to the north-east of the North Cape (29.56 inches). In July there is a minimum of pressure (29.80 inches) over central Norway (61° N. lat.). Along the part of the country adjoining the coastal region we have a maximum zone with a pressure of 29.85. In the sea between Iceland and Norway a trifling minimum (29.76 inches) occurs. It is obvious that the distribution of pressure must be regulated by that of temperature,—a maximum pressure of air over the colder, a minimum over the warmer localities.

As a consequence of this normal distribution of the pressure of the air the prevailing winds in winter blow from the land to the sea, with a deviation to the right. These are accordingly north-easterly along the Skagerrak, southerly along the west coast, south-westerly in northern Norway. They are for the most part cold winds, and cool down the surface of the sea throughout the nearest tracts. In summer sea-winds prevail; they blow along the land with the land to the left, more especially in southern Norway, where the coast of the Skagerrak has south-westerly, Lindesnæs westerly, and the west coast northerly winds. In northern Norway the prevailing summer winds are northerly. The winds blowing along the coast, in one direction or another, up or down, are twice as numerous as those blowing across it, from the land or the sea. In accordance with the greater value of the normal gradient in winter than in summer, the force of the wind on the coast is greatest in winter; during that season it rarely ceases to blow on the coast; but the number of calm days is very considerable in the interior of the country in and around the locality of the maximum barometric pressure. In summer calm weather is comparatively frequent on the coast (maximum zone of pressure), but not to the same extent in the interior. Upon the whole, the force of the wind on the coast is at all seasons of the year much greater than in the inland tracts. Storms are frequent on the coast (30 stormy days a year), rare in the interior (4 stormy days a year). Their most frequent direction is the same as that of the prevailing winds, viz., for the whole country on an average from the south-west, then from the west and the north-west. They are most frequent in winter, particularly during December and January (4 a month), rarest in summer (hardly 1 a month).

The amount of cloud in Norway is on the whole considerable. The coast of Finmark has the largest proportion (upwards of 3 cloudy days to 1 clear day). In the interior of the country the amount of cloud approximates 50 per cent. The summer months are somewhat clearer than those of winter.

Fog is most frequent on the west coast and the coast of Finmark in summer, rarest in winter. In the south-east part of the country the reverse is the case. In winter a frosty fog hangs over the inner extremities of the fjords when the cold is severe and the wind blows out from the land over the open water of the fjord.

The number of days with rain or snow is upon the whole greatest on the coast, from Jæderen to Vardö, least in the south-east part of the country. At the North Cape, in the Lofotens, along the west coast between Stad and Sogne Fjord, precipitation occurs on as many as 200 days of the year. On the Dovre Fjeld and on the coast bordering the Skagerrak the number of rainy days amounts to about 100 a year. The number of days with snow is least at Lister, increasing from 20 a year in that locality to 50 on the coast of Nordland in the vicinity of Throndhjem Fjord, on the Dovre Fjeld, and in Christiania, to 90 at Andenæs and Vardö, and to 100 at the North Cape. From Vardö to Andenæs, on the Dovre chain, and in the high mountain tracts snow occurs more frequently than rain. Snow can

fall on the coast in all months of the year from the North Cape to the Lofotens. The amount of precipitation is greatest on the coast, between Sogne Fjord and Stad, where it amounts to 77 inches. West of a line from the coast of Romsdal to Christiansand it is above 40 inches. In the Lofotens it reaches 45 inches. Throughout the south-east and in Finmark it falls as low as 12 inches. In the former region, however, exceptions occur; thus, for example, a short distance north of Christiania the annual rainfall is 40 inches, whereas in the city itself it amounts to only 26 inches. In the south-east the amount of precipitation is greatest during the months of July and August, on the west coast late in autumn or in the beginning of winter. The amount of precipitation is least in spring.

Thunderstorms are not very frequent in Norway. They occur chiefly in summer, either during rainy weather and with southerly to south-westerly winds or (especially throughout the interior) on very hot days. In winter the heavy gales from the west and south-west on the west coast are often accompanied with thunder and lightning of an exceedingly dangerous character, the clouds hanging very low. Not less than a hundred churches in Norway have been struck and destroyed by lightning during the last 150 years, and of these not less than forty on the coast, in the winter thunderstorms, as far north as the Lofotens. At the North Cape, too, thunderstorms occur in winter.