1. Properties of the Atmosphere
Earth Science
Chapter 11, Section 2

2. Temperature Measure of kinetic energy Two types of measures
How fast the particles are moving
Two types of measures
Fahrenheit (F) Used mainly in the US
Celsius (C)
SI Unit for temperature Kelvin (K)
0˚ K is called absolute zero- the coldest temperature any substance can have.
Temperature

3. The force exerted on an object by the weight of th atmosphere
Measured in
N/m2 (Newton divide by square meters)
mb (millibars) = 100 N/m2
At sea level the atmosphere exerts about 100,000 N/m2 or 100,000 mb
Air pressure decreases with altitude
Air Pressure

4. Density of Air Density = mass/volume Air is most dense at sea level
Density decreases with altitude
Density of Air

5. Pressure-Temperature-Density Relationship
Air Pressure and temperature
Pressure increases the collisions on the inside of a container
Particles are moving faster
Fast particles increase temperature
Pressure-Temperature-Density Relationship

6. Pressure-Temperature-Pressure Relationship
Air pressure and Density
With no change in temperature but added air to a containter
Density increases
Volume did not change, but the mass did
More force exerted on the walls of the container
Pressure-Temperature-Pressure Relationship

7. Pressure-Temperature-Pressure Relationship
Temperature and Density
Heating air in a balloon causes it to expand and increase volume
If air in a balloon decreases in temperature it gets smaller (less volume)
Pressure-Temperature-Pressure Relationship

8. Temperature Inversion
An increase in temperature with height in an atmospheric layer
Warm air on the top of cold air
Temperature Inversion

9. Wind Wind is air in motion
Wind happens when there are differences in atmospheric pressure
Due to the uneven absorption of solar radiation
Warm and cold air have different densities
Wind

10. Wind and Pressure Differences
Unequal density difference are produced by uneven heating
Air pressure increases as density increases
More air in the same space
Air moves from regions of high pressure to areas of low pressure
Wind and Pressure Differences

11. Wind Speed and Altitude
On Earth’s surface wind is slowed by trees, buildings, hills, etc.
Higher altitudes have less obstacles and wind speed is higher.
Wind Speed and Altitude

12. Humidity Amount of water vapor in the atmosphere Saturation
Occurs when the amount of water vapor in the atmosphere reaches the maximum amount.
Can’t hold any more water vapor
Relative humidity
Amount of water vapor in a volume of air relative to the amount of water vapor needed for the volume of air to reach saturation
Expressed as a percentage
Humidity
saturation

13. Temperature to which air must cooled at constant pressure to reach saturation
If dew point is nearly the same as the air temperature, relative humidity is high.
Dew Point

14. Extra thermal energy contained in water vapor compared to liquid water
Water vapor contains more thermal energy than liquid water
It had to be heated to turn to vapor
When this energy is released, condensation occurs
Latent Heat

15. Condensation Level Adiabatic process:
Air mass can change temperature with out being heated or cooled
Air heated by compression
Air cooling when it expands
Condensation Level