Lecture 2

Question 1

Troposphere

Answer 1

(0-20km) decrease of temperature with altitude. It is 75% of atmospheres mass and contains 99% of waters and aerosols.

Question 2

Troposphere structure

Answer 2

Boundary layer is 0-3km. Winds are affected by the surface causing turbulence to help vertical mixing

Free troposphere is 3-20km. winds are affected by the surface but mainly have laminar flow. Vertical mixing is weak

Question 3

How long does it take particles to traverse in troposphere?

Answer 3

Boundary layer –> 1-2 days
Free troposphere –> 1 week-1 month
Troposphere –> 5-10 years

Question 4

What is the tropopause

Answer 4

3km layer that keeps stuff in. Temperature stops decreasing with altitude.

Question 5

How can molecules get into the stratosphere?

Answer 5

Volcanic eruptions, Thunderstorms, Cloud formations, Airplanes

Question 6

Sources of trace gases in troposphere

Answer 6

biosphere (biological activity), biomass burning, volcanoes, lightning, industry

Question 7

Stratosphere

Answer 7

(20-50km). Begins at troposphere. Contains 20% of total mass of the atmosphere

Question 8

Stratosphere temperature

Answer 8

Has a large temperature inversion, with very little convection. Horizontal mixing occurs due to absorption of UV radiation by Ozone

Question 9

Mesosphere

Answer 9

(50-80km) begins at the stratopause. Contains 0.1% of total atmospheric mass

Question 10

Mesosphere temperature

Answer 10

Temp decreases with altitude

Question 11

Thermosphere

Answer 11

(80-700km) begins at the mesopause, start of heterosphere. Contains many ionic species and free electrons

Question 12

Thermosphere temperature

Answer 12

Temperature increases with altitude and varies with solar radiation. Causes particles to become electrically changed.

Question 13

Ionosphere

Answer 13

Region where ions predominate. located at top of mesosphere to exosphere

Question 14

Molecular diffusion

Answer 14

Random molecular motion that is molar mass and gravity dependent. Tends to produce an atmosphere in which molar masses of the gases gradually decrease with height

Question 15

Bulk Motion

Answer 15

Convection (heat transfer), turbulence (dynamic & motion). The mixing of air on the macroscale level is not affected by molar mass

Question 16

Homosphere mixing

Answer 16

Bulk motion strongly predominates therefor the composition of the atmosphere is independent of altitude

Question 17

Heterosphere mixing

Answer 17

Molecular diffusion predominates the motion. Strongly affected by gravity which results in stratification by molar mass.

Question 18

Heteropsphere mixing sections

Answer 18

less than 80km –> mean free path is short, bulk motion is fast

80-100km –> turbopause (transition between turbulent mixing and molecular diffusion)

100km –> mean free path is long, bulk motion is slow

Question 19

Fractionation of the heterosphere

Answer 19

200km –> increase in lighter MW gases. N2 drops off

500km –> predominately atomic O average air MW decreases to 16

greater than 500km –> Mean free path is so long that gas follows a ballistic trajectory

Greater than 100km –> H & He dominate air. MW is 1