Reading the WeatherLongstreth, T. Morris (Thomas Morris)
Science
Reading the Weather
Longstreth, T. Morris (Thomas Morris)
Weather forecasting
Suppose that our cyclone, this organization of warm, moist air with its
curving winds, enters the state of Washington on a Wednesday, from the
North Pacific. As early as the Monday afternoon before the wind throughout
all that section of the country would have shifted out of the west and
have started to blow in some easterly direction,--northeast in British
Columbia and southeast in lower Idaho. But since these winds are blowing
from the interior they are dry, and consequently rain does not fall much
before the storm center is near, that is on the Wednesday. If the storm
center passes north of Tacoma the winds, shifting by south and southwest,
bring in the ocean moisture and heavy rain commences which continues until
the rising barometer and westerly winds indicate the approach of another
anticyclone. So much for western Washington.
As the cyclone passes eastward it mounts the Cascades and its temperature
is lowered, its moisture is squeezed out, and it stalks over Montana, the
mere ghost of its former self, as far as energy and rainfall are
concerned. To be sure it preserves its essential characteristics of
relative warmth, and inwhirling winds. But let it continue. As its
influence begins to be felt over Wisconsin and the Lake region the moister
air is sucked into the whirl and rain, evaporated from Superior, falls on
Minnesota. The east winds are the humid ones now, the west ones the dry.
Eastward the center moves, over Indiana, Ohio, New York, the rainfall
steadily increasing as the ocean reservoirs are tapped.
The first time you tell a New Englander that his easterly storms come from
the west you are in danger, unless he be a child, for it is to the
children that one may safely appeal. Indeed it is the increasing number of
children who are learning these fundamental weather facts in the public
schools that the Weather Bureau relies upon for a more intelligent support
in the next generation. They teach their parents. These latter find it
difficult to believe, however, that the storms which hurl the fishing
fleets upon the coast in a blinding northeaster have not originated far
out at sea, but have come across the continent. For the safe handling of
boats knowledge of the rotary motion of storms is necessary that one may
be able to tell by the direction of the winds and the way they are
shifting where lies the center of the storm and its greatest intensity.
In Tacoma when the wind shifted by way of southeast, south, and southwest
that was proof that the storm center was passing north of the city.
Likewise if in New York the winds shift by way of northeast, north, and
northwest the storm center is passing south of that city. As it drifts out
to sea it is gradually dissipated by the changing influences on the North
Atlantic. Very few of our storms ever reach Europe, although some have
been traced to Siberia.
Public-domain text, read in full here on John Shaqi.
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