Page:Physical Geography of the Sea and its Meteorology.djvu/166

140 in the mountains, and the clouds gradually overspread the whole sky. But for the wind, which again springs up, it would be alarming to the sailor, who is helpless in a calm. What change will take place in the air? The experienced seaman, who has to work against the trade-wind or against the monsoon, is off the coast, in order to take advantage of the land breeze (the destroyer of the trade) so soon as it shall come. He rejoices when the air is released from the land and the breeze comes, at first feebly, but afterward growing stronger, as usual during the whole night. If the land breeze meets with a squall, then it is brief, and becomes feeble and uncertain. We sometimes find then the permanent sea breeze close to the coast, which otherwise remains twenty or more English miles from it. One is not always certain to get the land breeze at the fixed time. It sometimes suffers itself to be waited for; sometimes it tarries the whole night long. During the greatest part of the rainy season, the land breeze in the Java Sea cannot be depended upon. This is readily explained according to the theory which ascribes the origin of the sea and land breezes to the heating of the soil by day, and the cooling by means of radiation by night; for, during the rainy season, the clouds extend over land and sea, interrupting the sun's rays by day and the radiation of heat by night, thus preventing the variations of temperature; and from these variations, according to this theory, the land and sea breezes arise. Yet there are other tropical regions where the land and sea breezes, even in the rainy season, regularly succeed each other."

317. Sanitary influences of land and sea breezes.—One of the causes which make the west coast of Africa so very unhealthy when compared with places in corresponding latitudes on the opposite side of the Atlantic, as in Brazil, is no doubt owing to the difference in the land and sea breezes on the two sides. On the coast of Africa the land breeze is "universally scorching hot." There the land breeze is the trade-wind. It has traversed the continent, sucking up by the way disease and pestilence from the dank places of the interior. Reeking with miasm, it reaches the coast. Peru is also within the trade-wind region, and the winds reach the west coast of South America, as they do the west coast of Africa, by an overland path; but, in the former case, instead of sweeping over dank places, they come cool and fresh