The greatest depressions of the barometer are with gales from S.E., S., or S.W.; the greatest elevations with winds from N.W., N., or N.E.
Sudden falls of the barometer with west wind are sometimes followed by violent storms from N.W. and N.
If a gale sets in from the E. or S.E., and the wind veers by the S., the barometer will continue falling until the wind becomes S.W., when a comparative lull may occur, after which the gale will be renewed, and the shifting of the wind towards the N.W. will be indicated by a fall of the thermometer as well as a rise of barometer.
If a change of weather is long foretold by the barometer, the longer the presaged weather will last, and vice versa. The sailor expresses this in the rhyme—
“Long foretold, long last;
Short warning—soon past.”
Many more rules have been laid down by the meteorological observers, for which we have no space here; but we will now give a few brief rules on the forecast of weather by the observation of natural phenomena, which are useful by themselves, but still more so when confirming the forecast we have made from the instruments.
A halo round the moon, especially if it appear distant and yet very distinct, indicates a gale of wind, and probably rain.
When high lands are shrouded in mists, south-west gales and rain may be expected.
If distant objects are very clear and raised by reflection, rain (possibly wind also) is near.
“Wind dogs,” which are like broken portions of a rainbow seen to windward in the morning, are very certain signs of a gale.