Meet a Meteorologist
Click's friend David George is a meteorologist—a scientist who studies the weather. He works in a television station and delivers the weather report on the evening news. One day Click stopped by to talk to David about wind and weather. Here's what they said.
David: Hi, Click. What brings you to the station today?
Click: Well, it's blowing pretty hard outside, and I needed to get in out of the wind.
David: Ah, yes. It's windy because of the low pressure system near our area.
Click: Low pressure system? What's that?
David: Before I explain about low pressure, I'd better talk about wind.
Click: Oh, I know all about wind. Wind is moving air!
David: Right! And that moving air is what drives weather around the world. The key thing to remember about weather and wind is that hot air rises and cold air sinks. Since some parts of Earth are really hot and some parts are really cold, there's a lot of rising and sinking air. And besides this up and down motion, the spinning of Earth makes wind curve and blow around.
Click: It could make a mouse dizzy just thinking about it.
David: Here's the tricky part. Cold, sinking air squeezes down with a lot of pressure. So we call this a high pressure system. Warm air rises, lifting pressure off the Earth. This is a low pressure system.
Click: But what does this have to do with how stormy it is today?
David: Well, when warm, moist air rises into the sky, clouds are formed. So low pressure systems usually bring bad weather. High pressure systems bring clear, pretty days.
Click: It sounds complicated to me. But this looks like a cool place to work.
David: I like it. It has everything I need to prepare my weather reports.
Click: Is this the camera you use when you're on TV? Can I take your picture?
David: Well, maybe we'd better wait till the cameraman gets here.
Click: OK. While we're waiting, can you tell me how you make your forecasts?
David: I use weather maps, satellite maps, radar displays—lots of things. I get weather information on these computers from all over the world.
Click: It was pretty cloudy when I got here. Does that mean it's going to rain?
David: It might. It might even be raining right now, higher up in the sky.
David: Well, not every raindrop hits the ground, you know. The same wind that creates clouds can keep raindrops—and even heavy hailstones—up in the sky. Let me show you.
Click: Hey, that's a hair dryer and a Ping-Pong ball!
David: Right. Imagine the Ping-Pong ball is a raindrop. The blowing air from the hair dryer is the wind lifting the raindrop. The wind is strong enough to keep raindrops and hailstones, and even whole clouds, in the air.
Click: Well, but clouds are light and fluffy.
David: Not really. In a rainstorm, the raindrops in the clouds get too heavy to be held up by the wind, and they fall to the ground. If we had a really heavy rain here, and it rained on this building for twenty minutes, there would be enough water to fill a swimming pool. So those clouds are as heavy as a swimming pool filled with water—and yet the upward motion of air can support their weight. Wind is strong stuff.
Click: I guess!
David: You know, Click, I have some instruments right outside to help me measure wind. Want to see?
David: The wind vane on the bottom shows which direction the wind is coming from. The anemometer—those little cups on top—measures how fast the wind is blowing. Both help me know what kind of weather to expect.
Click: Well, David, I expect I'm going to get blown away if I stay out here much longer. Good-bye and thanks!
David: Bye, Click—better get inside until this storm blows over!
- What kind of a day is it outside of the television station?
[anno: It is a stormy day.]
- What happens in a low pressure system?
[anno: Warm air rises off of the Earth in a low pressure system. The warm air forms clouds in the sky.]
- You wake up in the morning and look outside. You see a clear, blue sky. Is there a low pressure system or a high pressure system overhead?
[anno: There is a high pressure system overhead.]