A similar cold wind from Central France toward the Riviera is locally known as the Mistral. The cold winds from the south, which in crossing the plains of Patagonia, are turned eastward by the Andes, are called in Uruguay the pamperos, as their direction causes the popular belief that they originate in the pampas, or grassy plains. In Malta the cold wind becomes known as the gregale—in the Adriatic sea it is the tramontana; in Trieste and Dalmatia it is the bora. In New Zealand the corresponding cold blast comes from the south, and is known as the buster. When loaded with drifting snow, as in the blizzard of the United States, the cold wind of the Yenisei Valley, in Asia, is locally called the purga; in the steppes of Central Asia it is the bura.
Eastern Asia receives its prevailing cold current from the northwest; while western Asia and Europe receive their cold wave from the northeast, there being no range of mountains, as in America, to deflect the current, as the polar currents are disposed to follow the continents, having their origin in arctic lands; while for a similar reason the return trades reach their extremes on the ocean. Hence, lines drawn through the places which possess the same mean annual temperature reach a higher latitude at sea than on land.
These are the chief periodical winds of long periods. There is one other class to be noted: the diurnal land and sea breezes. These occur along all coasts, whether in the zone of trades or of variable winds; but the phenomenon is more strongly marked in the tropical regions, and in the summer of the temperate latitudes, because of the greater difference in the temperature of land and sea by day and by night.
During the hottest part of the day the air over the land frequently reaches a temperature of 100° Fahr., and even more, while that over the sea rarely rises above 80°. During the night the land radiates its heat with such rapidity that, towards morning, its atmosphere may be from 10° to 15° colder than that of the sea.
Soon after sunrise, the land being warmer than the sea, a sea breeze sets in, which increases in force until about three o’clock, when the difference of temperature is greatest. It then gradually diminishes until about sunset, when, the temperature of the land and sea having become equal, the atmosphere is at rest, the calm continuing for an hour or more.
Soon the land becomes cooler than the sea, and a gentle breeze from the former sets in. It increases in force as the night advances, becoming strongest a little before morning, when the temperature of the land is lowest; after which it rapidly dies away, and is succeeded by a calm, to be soon replaced by the sea breeze.
One other species of variable wind is to be noticed: the hot, dry, dust-laden blast from desert regions. Such occur more or less periodically, and are known by different names in different localities.
Tom Moore has told us that “love’s witchery” on the heart is
“Like the wind of the south o’er the summer lute blowing,
That hushed all its music, and withered its frame.”
The reference is to the simoom of Syria and Arabia. One who has not experienced this wind can have little idea of its oppressiveness. Apt to come at any hour during the hottest months of the year, with a temperature so great that a piece of silver exposed to it becomes hot enough to blister the flesh, and laden with the impalpable dust of the desert, vegetation is scorched and withered by it, and animals flee from it as from the pestilence. It may last but a short time: it may endure several days.