Song of the Wind
Nature Bulletin No. 318-A October 26, 1968
Forest Preserve District of Cook County
Richard B. Ogilvie, President
Roland F. Eisenbeis, Supt. of Conservation
SONG OF THE WIND
The wind is simply air in motion. Air has substance like wood or
water, it has pressure, it can acquire heat and hold a temperature, and
it can travel from place to place.... The air which affects our lives is a
layer seven or eight miles thick, called the troposphere, which is next
to the earth. This air has pressure (14.7 pounds per square inch at sea
level) and when various factors, one of which is temperature, cause
changes in this pressure, the air starts moving. We cannot see it. We
can hear it. The song of the wind is the most wonderful music on
earth, and at times the most terrifying in its angry moments.
Air, like water, gets hot and cold. A basic principle of the physics of
air is that cold air is heavier than warm air. Air masses warmed by the
sun in the tropics affect the whole earth. This tropical air, when heated
by a burning sun, becomes lighter and is forced upwards by the heavier
air in the regions around it. Part of it goes northward carrying heat
and water vapor. These winds, going toward the north, become the
"prevailing winds" for us.
The wind has no master; it knows no bounds. A great air mass can lie
stagnant far to the north of us for days and weeks. It grows colder and
colder and finally starts moving south, sounds like shrill trumpets
marking its journey. As it travels it reacts to the force caused by the
earth rotating on its axis, and then the moving air mass begins to
rotate within itself in a clockwise direction. The winds, born in the air
mass, blow around their stern parent, and also blow in all directions.
When great air masses, one cold and dry, the other warm and
moisture-laden, meet, a storm is born. Rain is also an instrument
which records the music of the wind.
The song of the wind depends upon the wind's intensity. This is
measured in prosaic terms of miles per hour and is described by the
weather man with a series of familiar terms. You can tell the wind
force by the lazy smoke drift of a mesquite fire in the desert "light", 1-
7 mph); by the uneasy movement of leaves and twigs on the ground
("gentle", 8-12 mph); by singing leaves in trees ("moderate" or "fresh"
13-18 or 19-24 mph), by whistling telephone wires ("strong", 25-38
mph); and by the sharp sounds of breaking limbs on trees and shingles
torn from roofs ("gale", 39-54 mph). The furious roar of the "whole
gale" (55-75 mph), and the "hurricane" (above 75 mph), which luckily
so few of us experience.
The wind hums, whistles, sings or shouts as it goes about its business
of planting seed, raising dust clouds, pushing storms hither and yon as
the seasons change. There is the soft murmur in the wind of spring,
containing idle gossip about flowers, bees, birds and gentle things. The
wind of summer, reacting to the powerhouse we call the sun, is fitful
and variable in its gypsy travels, and in its music reflects its
temperamental moods. Winter's wind is a churlish fellow.... This wind
lifts its voice in ribald and raucous song, shouting a mad ballad of the
north, of glaciers, of frigid and isolated mountain peaks, of a world of
ice and snow. The wind has many voices; each voice tells a different
tale. There is a wind voice for every season because only with the
wind, harsh or gentle, can the season sing its song. Listen to the wind
and the song it sings. Knowing the wind song, you'll better
understand the world in which we live.
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Update: June 2012