The Boy with the U. S. Weather Men Part 5

"There," said the Weather Man, "let them sleep a while. They'll be ready for a real breakfast in a couple of hours."

Though hungry himself, the Forecaster waited for three hours before awakening the lads. Anton, by nature a light sleeper, awoke easily and was refreshed, but the awakening of Ross was a real task. He had been on a severe strain for twenty-seven hours and Nature demanded sleep. At last, however, he was roused and after he had plunged his head in a pail of cold water, he felt as full of ginger as ever and ready to start on rescue work all over again.

"I'm just going to breakfast," the Forecaster announced. "Do you want to go along?"

"Do I? I should say I did! But I'm afraid, sir, that Anton and I will eat up everything in sight."

"You don't need to worry about that," the Forecaster replied, "my men have been hauling supplies all night. Why, Ross, there are over two thousand people homeless this morning, right around this district.

They've all got to eat breakfast, too, so you see even your best efforts won't seriously decrease the supply."

"I'm not so sure about that, sir," Ross said laughing, "right now I feel as though I could eat all you've gathered for the entire two thousand."

"Come and try, then," the Weather Man said, smiling. Then, turning to Anton, he continued, "Likely enough, some of your people will be at the big tent that's been put up. If they're not there, I'll send out a couple of the boys on horseback to cover both sides of the flooded area and pa.s.s the word that you're safe." He turned to the older boy. "I've already sent word to your father, Ross."

The boys thanked him and started down the levee. Owing to the continuous work of the night, the cave-in had gradually been filled up, averting a break at this point. The river, turbid and swollen, was swirling by, not more than three feet below the top of the levee.

"Is the water going down yet, Mr. Levin?" asked Ross. "It looks as though the rain were over."

"Yes," answered the Forecaster, "the rain is over, but the water's not going down yet. It's rising. I'm fairly sure that there won't be any more rain for a few days, fortunately, but I heard from Greenville this morning that the river was still rising. We can stand another nine or ten inches, but a foot would be serious. Of course, the break that flooded out Jackson's Hollow, where your place was, Anton, is relieving the pressure a little. We've been lucky here. I haven't heard of any loss of life so far. It's a nasty flood, but when the rainfall last week was reported as being so heavy, I knew we couldn't escape trouble."

"Is it just the rain that makes floods?" Anton asked.

"Just rain," was the laconic answer.

"Why is it," asked the younger boy, "that there's more rain one year than another?"

"If I could tell you that," the old Weather Forecaster replied, "I'd be the cleverest meteorologist in the world."

"But doesn't anybody know why it rains?"

"Certainly, we know why it rains."

"Why, Mr. Levin?"

The Forecaster pushed back his hat from his forehead and looked quizzically at the white-faced lad.

"You really want to know why rain comes? Very well, Anton, I'll try to tell you. Stop me, though, if you don't quite understand.

"The Earth goes whirling about in s.p.a.ce, revolving around the Sun, as you know, and it has, like a sort of skin around it, an envelope of air.

This air is kept from flying off by the force of gravity. You know what that is?"

"Yes, sir," the cripple answered, "it's what makes a stone fall to the ground."

"Exactly. Now the air is made up of little particles or molecules, like the stone, only, of course, not so heavy. They're heavy enough, though.

How much weight of air do you suppose you're carrying, Anton?"

The boy looked puzzled.

"I don't quite see what you mean, sir," he answered.

"Suppose you had a pea on your head, it wouldn't be heavy to carry, would it?"

"Why, no," answered the lad, laughing.

"Supposing you had a basket of peas, the basket being only about as big round as your head, but six feet high, that would make quite a load, wouldn't it?"

"I don't believe I could carry it," was the answer.

"And if the basket were sixty feet high, as high as a barn?"

"I'd be squashed under it."

"And if it were six miles high!"

"Why," answered Anton, "a basket six miles high, even if you filled it up with cotton fluff, would weigh tons and tons!"

"Well, my boy," said the Weather Forecaster, "you're carrying on the top of your head a column of air, not only six, but sixty miles high, yes, and more than that! You don't notice it, of course, because you're used to it, and your body is made to accommodate itself to that weight by your tissues being full of air at the same pressure. Just the same, not counting the weight which presses on your whole body, amounting to about seventeen tons, you're carrying on your head, at this minute, a weight of over six hundred pounds."

"Six hundred pounds! As much as if I were carrying three heavy men sitting on my head!"

"Every bit of it, and more, under certain conditions of the atmosphere.

This depends mainly on the circulation of the winds, especially those great movements a thousand miles in diameter known as 'lows' and 'highs'

or cyclones and anti-cyclones. In the United States, an anti-cyclone generally means fair weather, and in an anti-cyclone the barometric column rises. That's why a barometer helps to foretell weather some time in advance; it responds to the vast movements of the atmosphere rather than to local conditions.

"Of course, Anton, at sixty miles up, the air is so thin that it has hardly any weight. Indeed, we wouldn't know there was any air at that height but for the trail that shooting stars leave. A meteor glows because of friction, and in a vacuum there is no friction. Therefore there must be air at the vast heights where shooting stars are first seen."

"Could an aeroplane get up there?"

The Forecaster shook his head.

"Never," he answered. "Even six miles up, the air would be too thin to sustain the weight of an aeroplane unless the machine were flying at terrific velocity, and besides, at that height, there wouldn't be enough air for an aviator to breathe. At that, Anton, you can see for yourself that if the air is saturated with water vapor--and the cloud-bearing atmosphere is eight or ten miles thick--there is room for a lot of water."

"It's evaporation that puts water into the air, isn't it, sir?" asked Ross.

"Exactly. The sun is s.h.i.+ning 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.