1. Describing Weather (cont.) Ms. Cervera

2. Bellringer # 2 Dew Point 1. When does dew form? Why? 2. What do you think dew point indicates?

3. Today’s Objectives & Practices Students will be able to…  Relate humidity to cloud formation  Describe how humidity and relative humidity are related  Explain how saturation relates to dew point Constructing Explanations: Students will construct explanations that focus on explaining how or why dew forms at certain temperatures.

4. Dew Point in the Classroom What did we observe today?

5. Moisture in the Air Humidity  The amount of water vapor in the air is called humidity.  When the humidity is high, there is more water vapor in the air.  When air is saturated, it contains as much water vapor as possible Relative Humidity  The amount of water vapor present in the air compared to the maximum amount of water vapor the air could contain at the temperature is called relative humidity.

6. Dew Point  When the temperature decreases, the air can hold less moisture.  The dew point is the temperature at which air is fully saturated because of decreasing temperatures while holding the amount of moisture constant.

7. 1. Under what weather conditions would both the air temperature and the dew point be the same number? 2. Imagine that you are doing this activity again, on a day with similar air temperature. If you found that the dew point had increased, would this indicate that there was more moisture in the air, or less? Explain.

8. Clouds  Clouds are water droplets or ice crystals suspended in the atmosphere.  Clouds form when moisture in the air condenses on small particles of dust or other solids in the air  A cloud that forms near Earth’s surface is called fog. How are clouds classified?

9. Cirrus – feathery of fibrous clouds made of ice crystals -indicate that rain or snow will fall within several hours Cumulus- fluffy and white with flat bottoms - associated with fair weather - produce thunderstorms when they get larger and darker on the bottom Stratus- smooth gray clouds that cover the whole sky -associated with light rain and drizzle -result in fog when formed close to the ground