2.4 Human Impact

Question 1

Effect of Urban Areas on temperature

Answer 1

Temperature
- 1 degree higher daytime
- 1.5 degrees higher at night

Question 2

Why do they effect temperature

Answer 2

Albedo
- Tarmac 10%
- Concrete17%
- Grass 24%

Materials
- 6x higher thermal capacity than agricultural areas
- 2x absorption levels
- Higher SHC so re-released slowly at night so consistently warmer temps

Surface Area
- much larger
- more materials/surface to absorb heat

Pollutants
- help trap outgoing radiation
- creates a pollution dome

Question 3

How do they effect winds

Answer 3

• More friction between buildings
• 5% less wind speed
• more gusty

Question 4

Causes of Urban Heat Island

Answer 4

• Increased absorption due to material type, albedo, surface area & pollutants
• increased LW reflection back to earth due to pollutants
• anthropogenic heat source; release heat especially at night
• decreased evapotranspiration so less energy lost through latent heat

Question 5

Case Study

Answer 5

London
St James’ Park; Annual Mean Temperature: Approximately 12.0°C
Charlwood Surrey; Annual Mean Temperature: Approximately 10.6°C