y cyclone we do
not mean those cloud funnels commonly called by that name that form at
certain times of the year in certain sections of the country and produce
such destruction of life and property. These storms are usually confined
to a narrow strip and are short-lived. They arise undoubtedly from local
conditions. A description of these tornadoes--for such is their true
name--will be given in some future chapter.)

These centers of high and low pressure may be several hundred miles
apart. In the area of high pressure, if it is in the winter season, the
weather is unusually clear and cold, and generally clear and fairly cool
at any season, and while there may be some wind it is not so strong as
in the cyclone or low-pressure center. At this point it will be warmer
and winds will prevail, with rain or snow, the winds varying in
direction and intensity at a given point as the cyclone moves forward.
In the center of these cyclones and anti-cyclones there will be a region
of comparative calm, and the air is ascending at the center of the area
of low pressure while it is pouring in on all sides from the area of
high pressure where the air is compressed by a downward current from the
upper regions.

The high-pressure or anti-cyclone system usually covers a larger area
than the low-pressure system, where the air is ascending. While the air
moves laterally from high to low, it does not move in a direct line. The
air movement outside of the high-pressure center is usually not at a
very high speed, but in northern latitudes in the direction of the hands
of a clock. As it circles around it widens out spirally until it reaches
the edge of a low-pressure system, when it bends in its course and moves
in the other direction around this center, but constantly moving inward
toward it in a spiral form and in a direction that is reverse to that of
the hands of a clock. When the air current comes within the influence
of a low-pressure or cyclonic system the velocity of its movement is
very much accelerated until it has moved into the zone of quiet air in
the center, where it is ascending.

In the upper regions of the atmosphere there are counter currents
flowing in the opposite direction. The downward flow at the area of high
pressure compresses the air near the surface of the earth and rarefies
it in the higher regions of the atmosphere, while the opposite effect is
going on over the center of low pressure, the air being rarefied neare