7.3 - Thermal Inversion

Question 1

Urban Heat Island Effect

Answer 1

Urban areas tend to have higher surface and air temperature than surrounding suburban and rural areas due to:
- Lower albedo: concrete and asphalt absorb more of sun’s energy than areas with more vegetation (absorbed sunlight is given off as IR radiation - heat)
- Lesseveporation: water eveporating from srfaces and transpiration from plants carries heat to surface into the atmosphere
- this cools off rural and suburban areas which have more vegetation

Question 2

Thermal Inversion

Answer 2

• normally the atmosphere is warmest at erath’s surface, and cools as altidude rises
  During thermal inversion, a cooler air mass becomes trapped near earth’s surface (inverting normal gradient)
  - due to warm fron moving in over it
  - or due to hot urban surfaces cooling overnight wile IR radiation absorbed during the day is still being released
• Because warm air rises, air convection carries air pollutants away from erth’s surface and distributes them higher into the atmosphere
• Because cold air at the surface is trapped beneath the waremr mass above, convection doesn’t carry pollutants up and away

Question 3

Effects of thermal Inversion

Answer 3

• Air pollutants (smog, PM, ozone, SO2, NOx) trapped closer to earth
• Respiratory Irritant: asthma flare ups leading to hospitilization, worsened COPD, emphysema
• decreased tourism revenue
• decreased photsynthesis rate