1. Chapter 1 The Atmosphere Section 3 Air Pressure

2. Properties of Matter (Stuff) Mass, Volume, Density, and Pressure All of the matter in the universe has these properties, no matter how big or how small it may seem to us. We know how to find the mass, volume, and density of a solid and of a liquid… but what about air?

3. What About Air? Does air have mass? Does air have volume?

4. How Do We Find Out If Air Has Mass and Volume?

5. Properties of Air Because air has mass and volume, we can find its density (the amount of mass in a given volume) by solving the density formula: Density = mass/volume D = m/v

6. Properties of Air The force pushing on an area or surface is known as pressure. A denser substance exerts more pressure than a less dense substance. Air pressure is the result of the weight of a column of air pushing down on an area.

7. Properties of Air

8. Measuring Air Pressure A barometer is an instrument that is used to measure changes in air pressure. There are two kinds of barometers: mercury barometers and aneroid barometers. The main difference between these two is that mercury barometers use liquid, while aneroid barometers use springs and levers.

9. Measuring Air Pressure

10. Increasing Altitude As you go higher into the atmosphere (increase in altitude), the amount of air above you gets less and less, so the air pressure decreases. Because there is less air taking up all that space in the upper parts of the atmosphere, the air density also decreases.

11. Increasing Altitude