1. Chapter 23 Change of Phase

2. Phases of Matter: Plasma Gas Liquid Solid

5. Pressure and Temperature According to Gay-Lussac’s Law, as the pressure of a gas decreases, there is a corresponding decrease in the temperature. This is why the temperature of the air drops with increasing altitude.

6. Evaporation Evaporation is a change of phase from liquid to gas that takes place at the surface of a liquid. Temperature is related to kinetic energy and molecules in a liquid are constantly bumping into each other; some gain energy while others lose energy. Occasionally, some molecules gain enough energy to escape the surface of the liquid. They are now considered a vapor, molecules in the gaseous phase

7. Evaporation is a cooling process. When water molecules escape the surface of liquid water, they leave behind molecules with less kinetic energy. This results in a net cooling of the liquid.

9. The Water Cycle

10. Condensation The opposite process to evaporation is condensation Condensation is the changing of a gas to a liquid Condensation is a warming process Condensation of water vapor forms clouds

11. Types of Clouds

12. Pyrocumulus Cloud formed by forest fire :

13. Relative Humidity Relative Humidity is the amount of moisture in the air compared to what the air can "hold“ Warm air can hold more water vapor than cool air

14. Thunderstorms

15. Thunderstorms can spawn severe weather High Winds Lightning Hail Tornados Thunderstorms Thunderstorms can spawn severe weather High Winds Lightning Hail Tornados

16. Tornado Preparedness Move to an interior portion of your home or school, away from windows during a tornado Do not open windows to equalize pressure! This is a myth! Have evacuation routes planned out ahead of time Do not stay in your car. Your car can become a flying projectile with you in it!

17. Boiling Evaporation takes place at the surface of a liquid A change in phase from liquid to gas can also take place beneath the surface of a liquid The gas that forms beneath the surface causes bubbles to form These bubbles are buoyed upward to the surface where they escape, this change in phase is called boiling Boiling Evaporation takes place at the surface of a liquid A change in phase from liquid to gas can also take place beneath the surface of a liquid The gas that forms beneath the surface causes bubbles to form These bubbles are buoyed upward to the surface where they escape, this change in phase is called boiling

18. Freezing When energy is withdrawn from a liquid, molecular motion slows down until the forces of attraction between the molecules causes them to get closer to one another The molecules then vibrate about a fixed position which causes a solid to form. This change in phase from liquid to solid is called freezing If sugar or salt is dissolved in the water, the freezing temperature will be lowered. These “foreign” molecules or ions get in the way of water molecules that ordinarily would join them together in the ice crystal structure Freezing When energy is withdrawn from a liquid, molecular motion slows down until the forces of attraction between the molecules causes them to get closer to one another The molecules then vibrate about a fixed position which causes a solid to form. This change in phase from liquid to solid is called freezing If sugar or salt is dissolved in the water, the freezing temperature will be lowered. These “foreign” molecules or ions get in the way of water molecules that ordinarily would join them together in the ice crystal structure