1. Lab 2: Vertical Structure of the Atmosphere

2. Vertical Structure of the Atmosphere

3. Vertical Structure of the Atmosphere
The atmosphere is a compressible “fluid”
Molecules are pulled to the earth’s surface by gravity
Molecules are most compressed close to the earth’s surface
Few molecules exist in earth’s gravitational field beyond 100km
Considered arbitrary “top” to the atmosphere
90% of our atmosphere lies below 16km

4. Vertical Structure of the Atmosphere
Within the Atmosphere:
Density Decreases as Height Increases
Rate: For every 5.6 Km you go up in the atmosphere (ascend), there is ½ the atmospheric mass from when you started
Called % above (sea level)
If gravitational pull is largest at the surface of the earth, then that too will decrease as you ascend. Connection?

5. Vertical Structure of the Atmosphere
Lab says: “We can assume that 100% of the atmospheric mass lies above sea level and exerts a pressure of approximately 1000 millibars (mb)
Same rate applies as “% Above”. Every 5.6 km, half the pressure exists

6. Vertical Structure of the Atmosphere
Partial Pressure of Gas = Total Pressure (as determined by our graph) X Percentage of Gas in the Atmosphere Ex: 1000mb x .78 (percent of Nitrogen) = 780 mb

8. Vertical Structure of the Atmosphere

9. Vertical Structure of the Atmosphere
Lapse rate – the rate at which temperature changes with height
Describes the vertical temperature structure of the troposphere.

10. Vertical Structure of the Atmosphere
Pressure density AND temperature decrease with altitude
↑altitude = ↓air pressure & temperature
1km↑ in altitude = ↓ 6.5°C in air temperature

11. Vertical Structure of the Atmosphere
Troposphere: where most of the weather occurs
Temperature decreases as height increases
Tropopause: Point between Troposphere and Stratosphere where there is no change in temperature

12. Vertical Structure of the Atmosphere
Tropospheric Lapse Rate: takes an average*
Average air temperature at the surface of the earth is 15°C
Temperature decreases by 6.5°C per kilometer until 11,000 km
Why does it stop? Tropopause

13. Vertical Structure of the Atmosphere
Location of Tropopause varies with season & latitude: colder air has a higher density and lowers the height
Thickness depends on high temperature & thermal mixing
Highest in the tropics

14. Vertical Structure of the Atmosphere
Ozone warms quickly in the stratosphere
Absorbs heat from solar radiation and emits heat (perhaps stabilizing the decrease in the troposphere and increase in the stratosphere)
Stratosphere does not warm at the same rate (unlike the troposphere which cools at the same rate) This is due to the ozone layer
Ozone like urban heat island
Radiation heating