Characteristics of “Air”

2. Characteristics of “Air” • “Air” is a general term for the gases that make up our atmosphere • 78% Nitrogen • 21% Oxygen • “Air” has volume – it takes up space • Gases expand to fill their containers • Gases are easy to compress • “Air” has mass and weight

5. Air pressure • is the force exerted by the molecules that make up air • is the weight of air • decreases with altitude

6. #1 Water Wonder • Low air pressure inside cup because there is little air • High air pressure outside of cup, pushing up on the index card

7. #2 – Balloon Blowout

8. #3 – Bottle Business • Hot water warms and expands the air • Air cools and condenses, resulting in low pressure • Air outside of the jug has higher pressure than the air inside the jug

9. #4 – Candle Craziness • How is Candle Craziness similar to Bottle Business??? • Video

10. #5 – Balloon Bonanza • Low air pressure between balloons because the molecules don’t have time to touch the balloons’ surfaces as they rush by • High air pressure on the sides of the balloons

11. #6 – Silly Straws • One Straw – sucking lowers the air pressure inside your mouth and the high pressure outside pushes the liquid up the straw • Two Straws – air coming up second straw keeps the air pressures in equilibrium

12. #7 – Paper Pandemonium • The faster air moves, the more the air pressure decreases • Blowing air under the paper lowers the air pressure under the paper so the paper is pushed down • Blowing air over the paper lowers the air pressure over the paper so the paper is pushed up

13. #8 – Straw Sensation • Adding air inside bottle increases the air pressure in the bottle • The high pressure in the bottle pushes on water and forces it up the straw

14. Air Pressure • High Pressure – occurs when air is compressed • Low Pressure – occurs when air is expanded – occurs when air moves • High and Low pressure areas are relative • Air moves from areas of high pressure to areas of low pressure, in an effort to reach equilibrium • Air movement results in a force applied to objects

15. #9 – “Egg”straordinary Egg • Video

16. Wind • Created by differences in air pressure • The greater the difference, the faster the wind moves

17. What causes differences in air pressure?

18. What causes differences in air pressure? • Temperature Differences • Warm air rises because it is less dense than cooler air • When air rises, air pressure is low • Cool air falls because it is more dense than warmer air • When air falls, air pressure is high

19. Convection Currents • Observed only in liquids and gases • Warm substance rises and cool substance sinks

20. Air Pressure & Temperature • Inversely Proportional • As air pressure falls, temperature rises… • because less pressure means molecules can move around more, and movement leads to increased heat energy and higher temperatures • As air pressure rises, temperature falls… • because greater pressure means molecules are compressed and moving less

21. What causes differences in temperature?

22. What causes differencesin temperature? • Unequal heating of the Earth • Amount of Sunlight • Cloud Cover • Atmospheric Gases • Large Bodies of Water • Water takes longer to change temperature than land

23. Amount of Sunlight

24. Amount of Sunlight • Equator receives most direct sunlight • Poles receive least direct sunlight

25. Cloud Cover

26. Atmospheric Gases

27. Atmospheric Gases • Various gases absorb different amounts of solar energy • Many gases that absorb solar energy leads to warmer temperatures • Few gases that absorb solar energy leads to cooler temperatures

28. Large Bodies of Water

29. Large Bodies of Water