Lab 2 Vertical Structure of the Atmosphere Vertical

Lab 2: Vertical Structure of the Atmosphere

Vertical Structure of the Atmosphere

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 100 km – Considered arbitrary “top” to the atmosphere • 90% of our atmosphere lies below 16 km

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?

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

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

Vertical Structure of the Atmosphere

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

Vertical Structure of the Atmosphere Pressure density AND temperature decrease with altitude – ↑altitude = ↓air pressure & temperature – 1 km↑ in altitude = ↓ 6. 5°C in air temperature

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

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

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

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