Urban Heat Island effect

Question 1

UHI definition

Answer 1

A city or urban area that is significantly warmer than its surrounding rural areas due to human activities

Question 2

3 temperature differentials in Urban areas

Answer 2

Urban surfaces absorb and emit large amounts of radiation (low albedo’s)
Insulation of buildings, terrestrials and heating reduces diurnal effects
5-6”C hotter in London
Heat creates conditions needed for thunderstorms

Question 3

3 precipitation differentials in Urban areas

Answer 3

Rainfall rates downwind of cities increase 50%-115% affecting flora
Higher amounts of saturated air in cities due to wind not carrying it away
Heat generates convection currents and hot air can carry more water vapour

Question 4

3 air differentials

Answer 4

Industry adds water with pollutants to the air people breath
Dust and pollution act as condensation nuclei
Frictional drag from building prevents wind carrying fog and pollution away

Question 5

3 wind differentials

Answer 5

Venturi effect
Urban structures act as wind barriers creating turbulent air+eddies
On warm nights there are cold spiral inflows from surrounding areas

Question 6

UK impact of urban temperatures

Answer 6

Deaths from overheating homes triple to 7,000 by 2050

Question 7

2 UK managment strategies

Answer 7

Manchester 10% increase in green spaces will maintain temperatures until 2050
London using ground water to cool areas