1. Temperature, Pressure and Cloud Formation (Lesson 6)
Where do clouds come from and where do they go?

2. Where does the fog go?

3. Where does the fog go?

4. A Scientific Explanation (C-E-R):
Claim - What are you telling me? -The claim is like the thesis statement. Evidence - Prove it! -Provide at least two pieces of evidence to back up your claim. -If you have numerical data USE IT. -Your highest and lowest data is normally a good way to go. (Show the range.) Reasoning - Why does it work this way? -Provide the science behind the claim.

5. Where do clouds come from and where do they go?
Claim – Clouds form from water condensing into liquid droplets and disappear when the droplets evaporate back into an invisible gas. Evidence -We made a cloud in a bottle that disappeared (evaporated) when we squeezed the bottle and appeared again (condensed) when we let the bottle go. -There was also fog in the morning (condensation) and then as air heated the cloud disappeared (evaporated). Reasoning -As the pressure drops (like in the bottle) or the temperature drops (like the fog) the molecules move more slowly and then condense into water droplets to form clouds. -As the pressure goes up (like in the bottle) or the temperature goes up (like the fog) the molecules move more quickly and then evaporate into gas particles to make the clouds disappear.

6. Water Vapor vs. Water Droplets
Gas
Liquid

7. Water Vapor vs. Water Droplets
We Can’t See
(Invisible)
We Can See (Visible)

8. Water Vapor vs. Water Droplets
Faster Moving Molecules
Slower Moving Molecules

9. Water Vapor vs. Water Droplets
Condensation
Evaporation

10. Water Vapor vs. Water Droplets
Cooling Down
Warming Up

11. Water Vapor vs. Water Droplets
Decreasing Pressure
Increasing Pressure

12. Big Ideas:
Clouds are formed by condensation of water vapor (gas) into water droplets (liquid).
Clouds are dissipated (disappear) by evaporation of water droplets (liquid) into water vapor (gas).
Molecules are able to more easily condensate in lower pressure.
Low pressure is usually caused by an air mass rising. The water molecules in the air cool down, move more slowly and cling to a dust particle making a liquid droplet (condensation).

13. Big Ideas:
The “Weather” and “Humidity” BrainPOP Videos are really good resources for this next information.
Relative Humidity is the amount of moisture in the air compared to the amount of moisture the air can hold based on its temperature. (Warm air can hold more moisture than cooler air.)
The Dew Point is the temperature at which the air is saturated (100% Relative Humidity) and condensation starts.