Ferris, Richard. [from old catalog] · New York, T. Nelson and sons · leaf 29
the world. Theheating by the sun in one locality causes an expan-sion of air at that place, and cooler, denser air rushesin to fill the partial vacuum. In this way winds areproduced. So the air in which we are to fly is in a state ofconstant motion, which may be likened to the rushand swirl of… … The solid arrows show the directions of a cyclonic wind on the earths surface.At the centre the currents go directly upward. In the upper air above thecyclone the currents have the directions of the dotted arrows. wholly invisible, and must be met as they occur^without a moments warning. l^ext in…
Aeronautics
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