Page:Weather Facts and Predictions.djvu/27

 In Europe the coldest point of the compass is about N.E. in winter and N.W. in summer, and accordingly the warmest winter point is S.W. and the warmest summer point S.E.

When a calm is succeeded by a forward motion of the wind (E., S., W., N.) it seldom "backs," but if it back it will generally return to the point whence it started, before performing a complete circuit.

If the wind be S. for two or three days, it may be succeeded unexpectedly by a northerly breeze; but a northerly wind will not be followed by a southerly one till after the intervention of a period of E. wind.

As a main characteristic, a N. wind is cold; and an E. wind dry; a S. wind warm, but rarely wet; and a W. wind generally rainy.

If a S.S.E. wind commences to blow gently, it will freshen gradually. If the sky becomes overcast, the wind will rise and may shift towards the S.W.

If the wind veers, it attains its maximum intensity between W.S.W. and W.N.W., and it never remains long in N.W. and N.

A shifting of the wind backwards may be expected to presage atmospheric disturbance of greater or less intensity.

In spring, if the wind shifts through W. to N. we may expect the weather to clear up suddenly and night frosts to set in, even though the thermometer at a little height above the ground may not fall to 32°.

The only winds which can preserve their directions unaltered in passing over a large tract of country are due E. and due W. winds