Page:Weather Facts and Predictions.djvu/43

 and become N. winds, whilst E. winds commonly work round towards the warmer part of the compass.]

Snow can never fall when the temperature is very low. What sometimes appear to be snowflakes with a very low thermometer are rather spiculæ of ice dropped from a stratum of clouds belonging to a warmer current, which happens to be over-head at a great distance. These spiculæ passing in their fall through very dry air cannot increase in size, and therefore cannot assume the form of flakes, because flakes are aggregations of frozen material.

Sleet falls chiefly in winter and spring, and is very rarely an accompaniment of storms.

If the predominating hue is green, more rain may be expected; if red, wind and rain.

A morning rainbow is considered to prognosticate wet, stormy, weather. [Because at that time of day moisture ought to be diminishing; but the presence of rain shows that that is not the case; nay, more, that the moisture is really augmenting.]

An evening rainbow is a presage of fine weather. [Because the conditions under which a rainbow can then appear is the passing away of the rain-cloud to E.; in other words, a clearing up in the W., and that at a time of