He had thought that in the face of such near-tragedy, school schedule would be broken, the remaining flights for the day be put off. But no—already an instructor had swung round in quick reproof on a boy who had developed nerves and was begging off.
“Planes out for the next flight up!” barked the pilot. “Danger is the aviator’s schoolmaster—we must learn from everything.”
On his way to the hangar, Hal passed Fuz, already climbing in a cockpit, and whispered, “I’ve thought of something—am going to send you a message in the sky—listen for it.”
For the flyers in the sky, the rest of the afternoon was a busy time. With each student in his plane went a data board and on it he was to do map-work, but not the usual maps that land folks know.
This was the class in meteorology, or the study of the air itself. Hal Dane was finding that flying was a complex vocation. Acquiring aircraft knowledge required study in such varied directions—study of iron and steel and linen and silk, the compass and oils and combustion, and now today, the study of what effect the sun has on the earth.
The sun, Hal decided, was the cause of a great deal of trouble. As he studied, he found that the sun by shining brightly in the morning heated up the earth and the air above it. Then the warm air expanded and took up moisture. In the afternoon, when the sun began to go down, the air cooled and descended towards earth. And that was where troubles generated. In the cooling, particles of air moisture condensed, then electricity accumulated—then next, like as not, a thunderstorm burst.
An aviator had to know these and a million other things, so as to gauge oncoming air disturbances, and dodge twisters and storm winds by dropping to a calmer level, or rising above storm.
In the days of his old glider experiments, Hal had found for himself that winds are generally prevalent over waters, and that hills make rising currents one can soar upon.
Now this deeper study of winds and fogs, of up and down currents, of the startlingly strange effects that water, forests and deserts have upon air currents—all this fascinated him.
As he read the air-speed indication and the altitude on his instruments, his busy hand drew waves and spiral lines on his data board—his map, showing currents and lay-out of the air stratum he had been assigned to.