in which they occur. In southern California at certain
seasons of the year the inhabitants are afflicted with what they call a
desert wind that blows from the heated regions of Arizona toward the
Pacific Ocean. The temperature sometimes reaches 120 degrees Fahrenheit,
and persons have been known to perish from the effects of these hot
winds in open boats out on the water before they could reach land.

Hot winds prevail on the plains of Kansas during the months of July and
August that are phenomenal in their intensity, so much so that if they
were widespread and of long continuance, like the northern blizzard,
they would be attended with great loss of life and destruction to
vegetation. Fortunately, they come in narrow streaks and in most cases
do not blow more than from ten to thirty minutes at a time. These hot
belts are sometimes not over 100 feet wide, and again they are as much
as 500. They are so hot and dry that green leaves and grass are rendered
as dry as powder in a few minutes. These winds are probably caused by
the fact that at this season of the year, when the prevailing wind is
southwesterly, the air becomes heated to a great height, and are the
resulting effect of certain combinations of air currents in the higher
regions of the atmosphere that force the already heated air toward the
earth. As the air descends it is more and more compressed, which causes
it to become more and more heated. We have already described the heating
effect of compression upon air as shown by the experiment with the fire
syringe. It was shown that air at normal temperature could be suddenly
compressed into so small a space that the condensed heat, which was
before diffused through the whole bulk of air at normal pressure, was
sufficient to cause ignition. A cubic yard of air on the surface of the
earth would occupy a much larger space if carried a mile above it. From
this it is easy to see that if a volume of air at that height had a
temperature of 70 or 80 degrees it would be very hot when condensed into
a very much smaller volume, as it would be if it were forced down to the
surface of the earth. These winds are the result of some superior force
that is active in the upper regions of the atmosphere, because it is
natural for heated air to rise, and this is what happens when the power
that forced it down to the earth is no longer active to hold it there.

Reference has been made in a former chapter to tornado winds; they are
rat