PERIODICAL Wucips. Land and Sea Breezes.—These are the most general, as well as most easily explained, of the periodical winds. On the coast, within the tropics, a i breeze sets in from the sea in the morning, at first a mere breathing on the land, hut gradually it increases to a stiff breeze in the heat of the day, after which it sinks to a calm toward evening. Soon after, a contrary breeze springs up from the land, blows strongly seaward during the night, and dies away in the morning, giving place to the sea-breeze as before. These winds are caused during the day, by the land gettingmore heated than the sea, consequently the air over it ascends, and the cool air from the sea flows over on the land to supply its place; and during night, by the temperature of the land falling below that of the sea, and the air becoming thereby heavier and denser, flows over the sea as a land-breeze. It is within the tropics where sea-breezes are most marked and constant, because there the sun's heat is greatest, and atmospheric pressure practically uniform, except in those rare instances where it is disturbed by hurricanes. But in countries such as Great Britain, where atmospheric pressure is most commonly, to some extent, greater or less than that of surrounding regions, the strength of the wind blowing from the high to the low barometer is far stronger than that which would result from the disturbance caused by the unequal heating of land and water; and conse quently the sea-breeze is not felt. In the warm months, however, When barometers are
nearly uniform over northern and western Europe, there is a gentle sea-breeze all round Great Britain during the beat of the day, and a land-breeze during night. Thus on the coast of Berwickshire, during fine settled summer weather, when the temperature of the land is much warmer than that of the sea during the day, in the morning the wind is n.w. till about 10 A.m., when it veers to n., falling all the time, till finally it sinks to a calm. A little before noon it springs up from n.e. or e., veers to s.e. from 2 to 3 r.m., where it continues till 7 P.M., when it veers to s. and s.w., and gradually sinks to a calm. About sunset it springs up from w. and veers to n.w. during the night, where it con tinues till next morning. On the other hand, on the w. coast of Scotland, n.w. winds diminish in force toward sunset, giving rise to the weather saying: "The w. wind is a gentleman and goes to bed." Quite analogous to the land and sea breezes are the mon soons (q.v.), which are only the ii. trades drawn out of their course in summer by the heated regions of southern Asia—the s,w. monsoon being only a vast sea-breeze blowing on southern Asia, and continuing several months of the year.