Reading the WeatherLongstreth, T. Morris (Thomas Morris)
Science
Reading the Weather
Longstreth, T. Morris (Thomas Morris)
Weather forecasting
The well-developed cyclone in winter causes what we all know as a three
days' rain, although continuous precipitation rarely lasts over ten
hours. The rest of the time is occupied by general cloudiness with
occasional sprinkles and a final downpour as the wind shifts to the west
and the anticyclone nears. In summer the depressions, being shallower,
rarely cause continuous cloudiness for three days, although their
influence often lasts as long as that in the guise of a series of
thunderstorms. The line of storms extends several hundred miles,
bombarding all the towns from Albany to Richmond. These thunderstorms
sometimes achieve in an hour or two even greater results than their winter
relatives can accomplish in three days in the matter of rainfall, wind
velocity, and general destructiveness. Our wettest months are July and
August and not December and January.
The freedom of the wind has been the subject of much poetic and prosaic
license. As a matter of fact the wind is the veriest slave of all the
elements. It is harried about from cyclone to anticyclone, wound up in
tornadoes, directed hither and thither by changing temperatures. It blows,
not where it listeth, but where it has to. And circuitously at that. For
once the path of duty is not straight. That is another fact that the
Boston mechanic would have been slow to accept,--that the wind blows in
curves. A little consideration, however, of the fact that the wind is
perpetually unwinding in great curves from the anticyclone and winding up
on the cyclone will show that nowhere can it be blowing in a perfectly
straight line.
Thus it becomes the surest indication that a cyclone is to the west of one
if the wind blows from an easterly point. The storm is bound to move
toward the east, therefore the rapidity with which the clouds move and
thicken will signify when the area of precipitation will reach the
observer. The cycle of the storm is normally this: After a cloudless and
windless night a light air springs up from a little north of east. At the
same time strands of thin wavy clouds appear, very high up. They may be
seen to be moving from the southwest or northwest. Their velocity is
great. Their name is cirrus, and they are called mares' tails by the
sailors. They are followed by several hours of clear skies, usually; but
if the storm is smaller and close at hand there is no clear interval.
Public-domain text, read in full here on John Shaqi.
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