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Chapter 13. Lesson 2 Pages 464-467 Clouds. Clouds…. What are they? How do they stay in the air? Some are ice…how do they stay in the air? How do they form?. How do clouds form?. Clouds form when water vapor in the air condenses to form liquid water or ice crystals.
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Chapter 13 Lesson 2 Pages 464-467 Clouds
Clouds… • What are they? • How do they stay in the air? • Some are ice…how do they stay in the air? • How do they form?
How do clouds form? • Clouds form when water vapor in the air condenses to form liquid water or ice crystals. • Two conditions are needed for condensation • Cooling of the air • Presence of particles
Role of Cooling • Cool air holds less water vapor. • The temperature at which condensation begins is the dew point. • If the dew point is above freezing, water droplets form. • If it is below freezing, water vapor changes directly into ice crystals (snow!)
Role of Particles • For water to condense, there must be particles in the air for the water to condense onto. • This is why there is dew on the grass in the morning, not usually just floating in the air.