Danny Dunn and the Weather Machine Read Online Free PDF Page B

warned you, didn’t I?”
    â€œOh, don’t be so goopy, Joe,” said Irene. “Danny, what did happen? How could that cloud form? Where did all that water come from?”
    â€œWait a minute,” Danny protested. “One question at a time. I think I know how it happened.”
    Deliberately, he poured some of the warm lemonade into a clean test tube, and drank it down. Joe took another test tube and did the same, saying under his breath, “This is just like that horror movie, ‘Grandson of the Werewolf,’ where the guy drinks from a test tube and turns into a monster.”
    â€œGo on, Dan,” said Irene. “Speak up.”
    â€œWell,” said Danny, “you remember the Professor said his engine projected beams of charged particles? When I was studying up on weather, one of the theories I read about was that clouds form because water droplets condense around chilled particles.”
    â€œSlow down,” Joe interrupted. “What kind of particles? I don’t get it.”
    â€œOh, for instance, little bits of salt, scooped up from sea spray by the wind and carried high in the air. Or dust, or soot from chimneys, or pollen from plants—all kinds of very tiny specks. These are called nuclei . High up in the air, where it’s cold, they chill. Then moisture condenses around them out of the air and forms lots of little drops. Millions of ’em all together make a cloud.”
    He paused, frowning. “I couldn’t seem to find a clear statement about what makes a cloud turn into rain,” he went on. “In some cases, it seems that the top of a cloud gets very cold. The drops turn to ice and start falling, because they’re heavy, and as they fall they gather other drops around them and pretty soon they’re all falling. When they get to the warmer air below, they melt, and they’re rain. Maybe that’s what happened in the kitchen. Maybe not.”
    â€œWhat else could have happened?” Irene demanded.
    â€œYou know, the tiny particles projected by the machine were very cold. And the air in the kitchen was full of moisture. Steam was rising from the pot. The cold particles acted like nuclei. Water droplets formed around them and made a cloud. As it rose, and as the cold ray chilled it some more, it began to condense; it couldn’t hold all that water, and the water fell out. So it rained in the soup.”
    Irene, her elbows on the lab bench and her chin on her palms, stared intently at him. Then she sat up straight. “Why—why—this means we can end the drought!” she cried.
    â€œNo,” said Danny. “I thought of that. But it’s obvious that the machine will only make rain when the air is supersaturated—when it’s so full of moisture that it can’t hold any more. And the weather now is pretty dry, too dry for us to make a cloud outside. Anyway, I think the machine can only make little clouds, and miniature rainstorms.”
    Joe had been listening, wide-eyed. He jumped up so suddenly that he almost sent a rack of test tubes crashing to the floor. “Wow!” he yelled. “We’re rich!”
    â€œHey, take it easy,” Danny cautioned, grabbing the rack.
    â€œWhat are you talking about, Joe?” asked Irene.
    â€œWhy, don’t you see? This thing has a thousand uses around the house!” Joe waved his arms in the air. “A portable, pipeless shower bath—an easy way to wash dishes—a million uses!”
    â€œMaybe he’s right, for once,” said Danny. “If the air was damp enough, you could use it to sprinkle the lawn.”
    â€œThat’s right. And it could be used for washing your car,” said Irene. “Or to sprinkle clothes for ironing. Or to fill up wading pools.”
    â€œI wonder if the Professor realizes what the machine can do?” said Danny.
    â€œIf he doesn’t, he soon will,” Joe said. “Just