1. Chapter 1.2 Air Pressure pgs 10-14
Air Pressure Notes
Chapter 1.2 Air Pressure
pgs 10-14

2. Properties of Air
Mass – air is made of small particles (molecules) of different gases and has mass (and weight)
nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and other trace gases
Density – amount of mass in a given volume
(D = m/v)
Pressure – force pushing on an area or surface
air pressure is the weight of a column of air pushing down on an area
atmosphere is heavy, but pushes in all directions (down, up sideways)

3. Measuring Air Pressure
Barometer – instrument that measures air pressure
Units of Measure – there are several different ways to measure pressure
Inches of Mercury (Hg) – used in most weather reports
Millibars (mb) – used on weather maps
1 inch of mercury = millibars
There are other measures you’ll learn in Physical Science next year!

4. Altitude
Altitude (or elevation) – is the distance or height above sea level
As altitude increases, air pressure decreases
the higher you go, the less atmosphere is pressing down on you!
As air pressure decreases, density also decreases
the higher you go, the less molecules of air in a given volume
the higher you go, the less O2, the harder it is to breathe!!!