1. WEATHER What will the weather be?

2. WEATHER n Predicting the weather is a hard thing to do. It is easy to see what the weather is like right now by going outside and looking around. n But, something always happens to change the weather...

3. n It has been a bright and sunny Summer day. Jane and Tommy played in the sprinkler and had lots of fun. But then something happened. The wind began to blow and the air turned colder.

4. n What happened to Jane and Tommys bright, sunny day? There was cooler air that moved in from the north. It pushed out the warmer air The place where this happened is called a front.

5. n Where cold air pushes against warm air, we say there is a cold front. They move fast and the wind howls. The warm air is pushed out of the way. The rising air carries water in a gas form called water vapor.

6. n As the air rises, it cools, and the water vapor turns to liquid. High in the sky, the drops of liquid water clump together and make clouds.

7. n The clouds grow big and dark as more air rises. Then it rains and thunder and lightning may occur.

8. n If it is cold enough, snow falls. It all happens very fast. Cold fronts cause sudden storms, but they usually do not last long.

9. n Where warm air pushes against cold air, a warm from forms. They move slowly and the wind blows just a little. Wispy clouds cover the sky with a light shower or drizzle occurring.

10. n The people who study the weather and try to figure out what will happen are called meteorologists. They measure the temperature of the air at different places around Earth.

11. n They watch to see where the air moves, how fast it goes, and they also measure the water vapor in the air.

12. n Another thing meteorologists measure is air pressure. As the air pressure moves, the weather changes. When it is low, air is rising into the sky and the clouds get bigger, darker, and lots of rain falls.

13. n Most of the time, air pressure is high, the skies stay clear, and it is warm, dry, and sunny.

14. n Meteorologists send all the information they gather into the National Weather Service in Maryland. Huge computers plot out the information they are able to predict what the weather will be like for tomorrow.