The Atmosphere

Question 1

What is the composition of dry air?

Answer 1

N2 78% O2 20.9% Ar 0.9% CO2 0.03%

Question 2

How much % are other gases and pollutants?

Answer 2

0.004%

Question 3

What is used to divide the atmosphere into layers?

Answer 3

Temperature variation with altitude.

Question 4

What is the ozone layer?

Answer 4

0.000002% by volume, filters UVB radiation (290-320nm) - damages DNA in animals and plants.

Question 5

Properties of Chlorofluorocarbons

Answer 5

unreactive, solvents persistent in toposphere, decompose in stratosphere under UV.

Question 6

Uses of chlorofluorocarbons

Answer 6

aerosol propellants, foam blowing agents

Question 7

What are chlorine free radicals capable of?

Answer 7

catalytic decomposition of ozone

Question 8

Montreal Treaty 1990

Answer 8

inter-governmental action to ban CFCs by 2000

Question 9

Properties of layers in atmosphere?

Answer 9

relevent to air pollution, troposphere contains air we breathe and weather processes

Question 10

What is the Troposhere?

Answer 10

A steady decrease of temp. with altidtude (0.6 degrees per 100m) ending at Tropopause.

Question 11

What is the Stratosphere?

Answer 11

Reversal of T gradient with T at 10-20 degrees at 60km. Little water vapour, no precipitation. T rise due to UV and IR absorption by ozone.

Question 12

What is the Mesosphere?

Answer 12

Ozone concentration decreases rapidly with height and T falls to -70 degrees at Mesopause.

Question 13

What is the Ionosphere?

Answer 13

T rises with height at 1000 degrees at 800km due to UV absorption by O2 and N2 molecules. Air becomes ionized and reflects radiowaves.

Question 14

What happens to gas density?

Answer 14

Gas density decreases as altitude increases. Half of total mass found in lowest 5km