Atmospheric pressure and temperature

Question 1

Air pressure and air density vs altitude (annotated)

Answer 1

See notes

Question 2

Pressure at altitude (equation 1)

Answer 2

p(h) = p(o)exp(-mgh/kT)

Question 3

Concentration at temperature and pressure (equation 2)

Answer 3

[X] = aN(A)p(o)/10^6(b)RT

Question 4

Explain earth’s first atmosphere

Answer 4

Composed of H and He. Birth of sun where nuclear reactions were enhanced, where solar winds and densities increased.

Solar winds stripped H and He from earth, additional loss caused by escape via gravitational field.

Question 5

Explain earth’s second atmosphere

Answer 5

Composed of CO2, H2

Initially caused by: volcanoes, fumaroles, steam wells, geysers.

OH molecules converting reduced gases into oxidised gases.

Outgassed water vapour condensed down to form the oceans.

Question 6

Using ideal gas equation in atmospheric chemistry

Answer 6

pV=nRT

Question 7

Draw an air temperature vs altitude graph (annotated)

Answer 7

Checklist of annotations:

1. -100dgC - 20dgC (X-axis labelled)
2. 0-120km (Y-axis labelled)
3. 0-10km (troposphere) 10-20km (tropopause) [-10dgC to (-60dgC)]
4. 20-40km (stratosphere = ozone) 40-60km (stratopause) [-60dgC to 0dgC for 20-50km] then [0dgC to -100 dgC till 80km] where 60-80km (mesosphere = ionosphere D region)
5. 80-100km [where temp const(straight up) for 80-90km then -100dgC to 20dgC] for after -60dgC height =100km where all above = thermosphere = ionosphere E region

Question 8

List all different layers in atmosphere

Answer 8

Troposphere, stratosphere, mesosphere, thermosphere

Question 9

Main characteristics of troposphere

Answer 9

High Temperature, Low height (radiative transfer)

Question 10

Main characteristics of stratosphere

Answer 10

Negative lapse rate form inversions. Stable against vertical motion.

Temperature rises due to absorption of solar radiation by ozone

Question 11

Main characteristics of mesosphere

Answer 11

Temperature decrease with height where lapse rate is sub adiabatic therefore no convection

Question 12

Main characteristics of thermosphere

Answer 12

Temperature increase towards infinity but space is cold. Low density meaning no frequent collisions and lack of equilibration between degrees of freedom