Open main menu

Page:Popular Science Monthly Volume 32.djvu/499

This page has been proofread, but needs to be validated.
481
THE MOON AND THE WEATHER.

the clouds is increased radiation from the earth's surface, producing a reduction of temperature in the air near the ground; and Mr. Park Harrison, who discussed a series of temperature observations made at Oxford, Greenwich, and Berlin, found a mean decrease of more than 2° F. about the time of full moon. The French proverb of la lune rousse, which Louis XVIII bewildered Laplace by asking him to explain, may be accounted for by the aid of these researches. The name of "red moon" is applied to the moon which is full at the end of April or early in May, because during the clear nights which then prevail, the tender leaves and buds are frozen and turn red; and popular superstition attributes this effect to the peculiar action of the "red moon's" rays. It is at least curious that the connection assumed in this superstition between the full moon, clear nights, and May frosts should be one that is suggested by independent scientific results.

Apart from any question of lunar influences, however, there are many popular prognostics which make use of the moon merely as a convenient exhibitor of certain atmospheric effects—effects which would not be visible without the moon to show them up, but in the production of which that orb plays no part whatever; and in so far as sweeping denunciations of lunar weather proverbs include these, discredit is thrown on a class of useful sayings very unjustly.

There is, perhaps, no better known lunar prognostic than that referred to in the old Scotch ballad of Sir Patrick Spens:

"O ever alack! my master dear,
I fear a deadly storm.
I saw the new moon late yestreen,
Wi' the auld moon in her arm;
And if ye gang to sea, maister,
I fear will suffer harm."

Chambers, in "The Book of Days," says that to see "the old moon in the arms of the new one" is reckoned a sign of fine weather—another curious example of how sayings get twisted; but in that statement he is quite wrong. The appearance is almost universally held, to be a sign of bad weather. Two explanations have been offered to account for the prognostic, in each of which there is undoubtedly a measure of truth. When the moon appears "new" to us, the earth would appear "full" to the lunar inhabitants, if there were any; and what causes the dark part of the young moon to be dimly visible is its reflection of the brilliant earth-shine. The earth, however, will not always shine with equal brilliance, even when the same amount of surface is illuminated, for obviously clouds reflect more light than either land or sea. Hence, when an unusual illumination of the night-side of the moon is apparent, it shows that the earth-shine is exceptionally strong, which in turn is an indication of the presence of a large amount of cloud in our atmosphere. Further, as a moment's consideration will prove, the cloud area must lie to the west of us, the direction from