1. Air Pressure 7.2 Density and Pressure of Air

2. The air is made up of molecules.

3. Properties of Air Eureka Density Density 2 Air has mass. Since air has mass, it has other properties, including density and pressure.

4. Density Amount of mass in a given volume Density = 5 circles per cube

5. Density Amount of mass in a given volume Density = 11 circles per cube

6. Temperature Affects Density Density = 6 circles per cube 2 circles per cube

7. Temperature Affects Density Density = 3 circles per cube 10 circles per cube

8. Which rises and which sinks? Density = 5 circles per balloon Density = 2 circles per balloon

9. Density Eureka Density Density 2 If the molecules are real close the density is higher. If the molecules are spread further apart the density is lower.

10. Density Which is Denser?

11. Which cookie has more chocolate chips? Cookie A is denser. It has more chocolate chips in the same size cookie than cookie B. If I wanted to make a cookie less dense I would use the same amount of chocolate chips just make the cookie bigger. AB

12. Which is state of water is least dense? Most dense? liquidSolidGas Molecules move very slowly! They are close together. Molecules move faster and are more spread apart. Molecules move very fast! They are very spread apart. Most Dense Least Dense Air and Density Clip

13. Density of warm and cold air. Warm Air Less Dense Molecules are further apart. Air is lighter. Cold Air more Dense Molecules are closer together. Air is heavier.

14. Warm Air Less Dense Molecules are further apart. Air is lighter. Cold Air more Dense Molecules are closer together. Air is heavier. Density? Molecular spacing? Weight? Temperature Density? Molecular spacing? Weight? Temperature Pair/ Share

15. Convection currents happen because hot air rises. It rises because it is less dense and lighter. Cold air sinks because it is more dense and heavier. Why do convection current occur?

16. Pair/Share Explain how a convection current works. Use words like: density, temperature, molecules, weight

17. Air Pressure and Altitude Most Dense Less Dense

18. 18 Gravity pulls the air molecules toward the earth, giving them weight. The weight of the air molecules all around us is called the air pressure.

19. The pressure acting on the surface of the earth is called atmospheric pressure. atmospheric pressure It is caused by the weight of a column of air pressing down on the surface of Earth. Atmospheric pressure is measured by a barometer. Atmospheric Pressure

20. 20 Air pressure is equal in all directions.

21. 21 to measure air pressure. A Barometer is used

22. An aneroid barometer uses a cell which has had most of the air removed. As the air pressure around the cell increases, it presses on the cell, which causes the needle to move. Barometer Clip Barometer Clip Barometer Clip MILLIBARS

23. The lower we travel down into the atmosphere the more weight there is above, and so the tighter the air is squished or compacted. Low altitude = high air pressure High altitude = low air pressure ALTITUDE AND AIR PRESSURE So why is it harder to breath at higher altitudes? Altitude vs Air pressure Clip

24. Since pressure changes with altitude… …how does changing altitude affect a barometer?

25. 25 As elevation goes up Barometric pressure goes down. This is an inverse relationship.

26. Can you feel air pressure? When you take off or land in an aircraft, your ears may hurt or feel uncomfortable. This is because your eardrums can feel changes in air pressure as the aircraft moves quickly up and down.

28. Astronauts wear space suits so the can pressurize themselves in the space suit. With out a space suit an astronaut would explode. More inside body pressure than outside pressure. Submarines have to be made very strong to withstand the enormous pressure exerted by the water. If they go too low in altitude they will implode. 9 min video on Air pressure

29. 29 Most aneroid barometers have a needle which can be set to remember the previous reading. Why would this be important?

30. 30 Changing Pressure A rising barometer = increasing air pressure. This usually means:

31. 31 Changing Pressure A falling barometer = decreasing air pressure. This usually means: Where’d the hula dancer go?

32. Why do baseball players like to play in Denver, Colorado?

33. Heat wind and pressure clip