Urban Climate

Question 1

Urban heat island

Answer 1

Phenomenon where urban areas are warmer than rural

Question 2

urban form of an UHI

Answer 2

hightest temperatures - industrial areas and most densely built up
eg CBD
areas of cooler air above parks and bodies of water - temperature sinks

plateaus - areas with same temperature, due to same land use

• temperature can change rapidly due to changing land use
  eg housing to CBD
  = temperature cliffs

Question 3

Causes of UHI

Answer 3

Air pollution - increase cloud cover, traps heat

Human activity - people, industry, vehicles create heat

Albedo - urban surfaces darker (tarmac) lower albedo, absorb heat

Less evapotranspiration - less vegetation, less heat energy used

Question 4

Variations to the UHI

Answer 4

Stronger at night
- rural areas cool faster, urban release heat absorbed in the day

Stronger in summer
- more solar radiation to absorb

Stronger in anticyclone- no cloud, more solar radiation

Question 5

Precipitation in urban areas

Answer 5

Rain is more frequent and intense

UHI, air warmer, can more evaporation, condensation and rain

Air pollution, dust creates condensation nuclei for water to condense on

Water vapour from industry

Question 6

Fogs and thunderstorm in urban areas

Answer 6

More pollution -> more condensation nuclei -> more fog

UHI, warmer, more evaporation so thunderstorms more likely

Question 7

Wind in urban areas

Answer 7

Wind slower - building cause friction, slows it down
Or cam shelter completely

Canyon effect - can cause powerful gusts as wind channeled down streets

Question 8

Snow and frost in urban areas

Answer 8

UHI, higher temperatures