Weather Systems

Question 1

What are the major forces generating air motion?

Answer 1

The Pressure Gradient Force (PGF)
The Coriolis Force
Centripetal force
Friction

Question 2

Which way does the Coriolis force deflect air flow in the southern hemisphere?

Answer 2

Left

Question 3

Which way does the Coriolis force deflect air flow in the northern hemisphere?

Answer 3

Right

Question 4

What characteristics are typical of an Anticyclone?

Answer 4

Closed high pressure system with a general west to east trending axis, anti clockwise rotation, upper level convergence and lower level divergence resulting in subsidence in between, and typically fine weather with light winds.

Question 5

What characteristics are typical of an extra-tropical cyclone (depression)?

Answer 5

Form in association with frontogenisis (fronts), clockwise rotation in southern hemisphere, often forms extensive stratus cloud fields (Air ascends, cools and then condenses to form clouds).

Question 6

What is a front?

Answer 6

The convergence zone of two air masses with distinctly different temperatures and humidity conditions, typically seen between two sub-tropical anticyclones.

Question 7

What characteristics are typical of a warm front?

Answer 7

Clouds can arrive up to 12 hours prior to surface front, rain is typically seen with clearing weather.

Question 8

what characteristics are typical of a cold front?

Answer 8

rain associated with rear facing ascent in concentrated frontal zone.
Prefront: Hot weather, northerlies, increased cloud cover.
Arrival: Fall in temperature, onset of rain, wind speed increase, thunderstorms.
Post-front: clearing weather as next front moves in.

Question 9

List the 6 forms of air pollution.

Answer 9

Natural, biogenic, anthropogenic
Particulates (Dust, ash, sea salts)
Gases (CO2, CH4, SO2)
Energy (Thermal pollution, radiation)
Noise
Smell

Question 10

What is ‘Suspended Particulate Matter’ and where does it come from?

Answer 10

Coarse mode - Mineral dusts (Asbestos, limestone, cement)
PM10 - Median diameter < 10μm
PM2.5 - Median diameter < 2.5μm
It comes mainly from, volcanoes, wind erosion, combustion of fuels and industrial processes.

Question 11

What are the main ozone destroying compounds?

Answer 11

Chlorine and Bromine compounds, primarily CFC’s (Chlorofluorocarbons).

Question 12

Describe the process that results in the formation of the ozone hole over the poles?

Answer 12

• Polar vortex forms through the isolation of the air in the stratosphere above the poles.
• Air temperatures fall to -80 degrees resulting in polar stratospheric clouds (PSC’s)
• PSC’s present favourable conditions for chlorine catalytic photochemistry that destroys ozone.

Question 13

What is the difference between ozone found in the stratosphere and ozone in the troposphere?

Answer 13

90% of atmostpheric ozone is found in the stratosphere, this ozone is beneficial as it acts as the primary UV radiation sheild. The remaining 10% of atmospheric ozone is found in the troposphere, this has toxic effects on humans and vegetation.

Question 14

What is smog?

Answer 14

Episodes of high surface ozone in urban and rural areas.