Atmosphere and weather 2.4

Question 1

What is the enhanced greenhouse effect?

Answer 1

The addition of greenhouse gases to the atmosphere by human activity.

Question 2

What are some examples of greenhouse gases?

Answer 2

• Increased burning of fossil fuels.
• Burning of rainforests
• Methane gas produced by domestic animals.
• CFC’s (aerosoles)
• Car fumes.

Question 3

What is the warming effect of a gas known as?

Answer 3

Radiative forcing

Question 4

What evidence is there for global warming?

Answer 4

• Increase in global temperature: up 0.7 since pre industrial
• Ocean salinity: more evaporation in dry areas such as west Indian Ocean
• Melting sea ice: decline of 2.4% per decade since 1980.
• Rising sea levels: rose by an average of 3.1mm per year since 1992
• Blanching of coral reefs
• Increased malaria from mosquitos moving into southern Europe.

Question 5

What is the average difference in summer temperatures between Vancouvers CBD and rural areas?

Answer 5

25 degrees in CBD.

15 degrees in rural.

Question 6

What is the reasons for Vancouvers high temperatures in the CBD?

Answer 6

• Brick, concrete and dark tarmac surfaces have a high SHC and low albedo.
• The greater the building density, the greater the heating.
• Tall buildings turn streets into ‘canyons’ which reduces sky view and smaller angle of heat loss.
• Large urban parks such as Stanley park are much wider so heat loss is much greater.
• Central heating, gas and heating from industrial sources warm the atmosphere.
• Higher rates of evapotranspiration.

Question 7

Why is the wind varied in Vancouver between CBD’s and rural areas?

Answer 7

• Wind is generally less strong in the city centre as tall buildings obstruct and deflect airflow and increase friction.
• Therefore, there are more calm days in the CBD than the rural areas.
• However, skyscrapers in the CBD can cause turbulence and vertical uplift with eddies in the lee of buildings.

Question 8

How is precipitation varied across Vancouver?

Answer 8

• An orographic effect is present as for every 100m increase in height, precipitation increases by approximately 100mm.
• 10% cloudier in the central city due to convection currents from urban-rural temperature differences.