1. 1

2. Precipitation 2

3. Rain, snow, sleet, and hail are all forms of precipitation 3 Vocabulary: precipitation Water that falls to Earth

4. 4 For rain to fall, the water drops in a cloud must reach a certain size

5. they combine like on this leaf 5 As the tiny droplets of water in a cloud bump into each other

6. 6 When the drops are heavy enough they fall as rain

7. 7 If the air is very cold water vapor in a cloud may freeze into tiny ice crystals called snow All snowflakes have six sides, or points

8. 8 If rain falls through a layer of very cold air before reaching the ground the drops will freeze

9. 9 They form pieces of ice called sleet Sleet forms only in cold weather

10. Hail may fall during a thunderstorm in the spring or summer 10 Hail begins as tiny pieces of ice in a thundercloud

11. The pieces of ice start to fall 11 but they are swept back up by a current of air

12. 12 As the pieces fall again they collect more water This water freezes, making the hail larger

13. This happens over and over again until the hail becomes so heavy it falls to the ground 13

14. 14 Sometimes you will find that blades of grass have drops of water on them even when it has not rained

15. This water is called dew 15 Vocabulary: dew Water vapor that condenses and forms drops of water as the air cools

16. Dew forms when there is a large amount of water vapor in the air 16

17. 17 so the water vapor condenses into drops of dew Cool air cannot hold as much moisture as warm air

18. 18 If the ground is very cold, the dew freezes and forms frost Vocabulary: frost Dew that has frozen