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Science We need cotton balls Do Now: 3/12 Can you bring some?

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Presentation on theme: "Science We need cotton balls Do Now: 3/12 Can you bring some?"— Presentation transcript:

1 Science We need cotton balls Do Now: 3/12 Can you bring some?
HW: Read 16-1 and study for quiz 1. Clear your table for the quiz Today ~ TTK 16:1 quiz and check ~ Complete PPT w/notes: Water in the Air

2 The Water Cycle The transfer of water between the atmosphere and Earth’s surface. Water evaporates from plants and bodies of water Water condenses in the atmosphere and forms clouds Clouds become saturated and water falls as precipitation to the surface Water runs off surface into lakes, streams and oceans.

3 What is Humidity? The amount of water vapor in the air.
As water evaporates it becomes water vapor. Water vapor is invisible. Warm air can hold more water vapor

4 What is Relative Humidity?
Amount of water vapor in the air compared to the amount of water the air can hold. A percentage % Air holds all the water vapor it can = Saturated = 100% RH

5 Figuring Relative Humidity
_actual water vapor content (g/m³)__ X 100 = RH saturation water vapor content(g/m³) 1 m³ of air at 10ºC has 5g of water vapor but, at this temperature it can hold 8g Calculate RH g X 100 = 63% 8 g Air holds 13g but can hold 25g 13 g X 100 = 52% 25 g

6 Factors Affecting Relative Humidity
The amount of water vapor The temperature If the water vapor stays the same: Temperature goes down RH%  up Temperature goes up RH%  down

7 How does that work??? Temperature ºC Saturated g 15 10 20 25
At 20 ºC with 15g of water vapor RH = 100% Temperature goes up to 25 ºC air could hold 20g So… 15g (what it has) X 100 = 75% 20g (what it could have)

8 Measuring Relative Humidity
1. Measured with a psychrometer 2. Has two thermometers * 1 wet bulb * 1 dry bulb Use the dry bulb temp and the chart

9 Determining Relative Humidity
Use your book; page 484 Determine the relative humidity for the following days Day DryºC WetºC DifferºC RH % Mon 16 18 Tue 20 Wed 21

10 Determining Relative Humidity
Day DryºC WetºC DifferºC RH % Mon 16 18 2 81 Tue 20 4 63 Wed 21 3 73

11 Condensation 1. Water vapor becomes a liquid
2. Happens when air is saturated 3. Air cools to 100% relative humidity

12 Dew Point Temperature at which the air is saturated & condensation occurs Where does the water on the outside of a glass come from??? The cold liquid in the glass cools the air outside of the glass Air next to the glass reaches its Dew Point Water vapor in the air condenses on the glass! Quick Lab: pg 485 What is the dew point temperature in the classroom today?

13 Clouds A collection on millions of tiny water droplets or ice crystals
Warm air rises  cools to dew point water vapor condenses to a liquid/solid Altitude and form/shape

14 Forms of Clouds Cumulus: Fluffy white with flat bottoms
Stratus: Form in layers, cover large areas of sky Cirrus: Thin, feathery form at high altitudes

15 Altitude of Clouds Cirro – forms at high altitude made of ice crystals
Alto – middle altitudes made of ice crystals & water droplets Low altitudes have no special prefix



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