In the Path of the Tornado.
A farm-house, with farm buildings in a copse of trees stood here; the buggy, after a flight through the air, was dropped, little injured.
Courtesy of T. B. Jennings, U. S. Weather Bureau, Topeka, Kans.
"Exactly. The sun is shining on some part of the earth all the time. There's never a second, day or night, that water is not being evaporated from the seas, from lakes, from rivers and from the earth itself. All the water that is taken up must fall somewhere, and all the rain that falls means that the atmosphere must fill itself with water vapor again. It's a continuous performance, and the water which is being evaporated into the air falls to the earth, sooner or later, as rain, hail, or snow."
"If it's all so regular," said Anton thoughtfully, "I don't see why we don't get the same amount of rain every day, or at least every season."
"It isn't regular at all," the Weather Forecaster explained. "If climatic conditions were regular, we could forecast the weather several years in advance, instead of only a few days. There are a thousand complicating factors. Land and sea are irregularly divided, and as there is more evaporation from the sea than the land, every little curve in a coast line means a disturbance of regularity. Then, Anton, remember, while the earth is almost a globe it is not perfectly round, so that every variation from the regular curve disturbs the air currents. Moreover, the motions of the earth are very complicated. Sometimes it is nearer the sun than at other times. It wobbles slightly on its axis. It is inclined to the plane of the ecliptic, causing the seasons, and that brings a new set of factors into the problem. A mountain range or a desert will modify the atmosphere, even the difference between a forest and a prairie is noticeable."
"Suppose you could figure all those things out, couldn't you foretell the weather, then?"
The Forecaster shook his head.
"Suppose you had a thousand marbles of different colors," he said, "and you dropped them from the top of a house to the hard ground below, a rough and rocky piece of ground, could you ever figure out what kind of a pattern they would make? You might measure the size of the marbles and compute how many times they would strike against each other in falling, meantime figuring the angles of direction that each collision would produce. You might measure the resistance of the ground and the elasticity of the marbles and estimate the manner in which they would bounce after striking the ground and the distance to which they would roll. After you had done all that, you might have the right to expect that you would know the pattern that the marbles would make as they lay scattered on the ground. But you would be wrong, for if you dropped those marbles a thousand, yes, a million times, the pattern would be different each time. After tens of billions of experiments you might be able to find the proportion of patterns, but the result would never be of practical use.