APES 7.3 & 7

7.3: THERMAL INVERSION

Why urban areas tend to have higher surface and air temperature than surrounding suburban and rural areas: lower albedo from absorption of sunlight from concrete and asphalt and less evapotranspiration, meaning more vegetated areas are cooled off

What happens during a thermal inversion: a cooler air mass becomes trapped near earth's surface due to a warm front moving in over it or hot urban surfaces cooling overnight while IR radiation absorbed during the day is still being released

Where do air pollutants go into the atmosphere without thermal inversion: because warm air rises, air convection carries air pollutants away from earth's surface and distributes them higher into the atmosphere

Where do air pollutants go during thermal inversion: because cold air at the surface is trapped beneath the warmer mass above, convection doesn’t carry pollutants up and away

Effects of thermal inversion: air pollutants trapped closer to earth, leading to respiratory irritation (asthma flareups, worsened COPD, emphysema, decreased tourism revenue and photosynthetic rate

7.4: ATMOSPHERIC CO2 AND PARTICULATES

natural sources air pollutants: lightning strikes as they convert N2 in atmosphere to NOx, forest fires (CO, PM, NOx), plants as they emit VOCs, and volcanoes (SO2, PM, CO, NOx)

Natural sources of CO2: respiration from all living things and aerobic decomposition

Natural PM sources: sea salt, pollen, ash from forest fires and volcanoes, dust (windborne soil), which leads to haze (scattering of sunlight and reduced visibility)

The natural source of CH4: anaerobic decomposition

Aerobic decomposition: decomposition of organic matter by bacteria and decomposition in the presence of oxygen

Anaerobic decomposition: decomposition of organic matter by bacteria and decomposition in low or oxygen-free conditions

Particulate matter: solid or liquid particles suspended in air

PM10 (<10 micrometers): particles or droplets like dust, pollen, ash, or mold; too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract and cause inflammation

PM2.5 (<2.5 micrometers): particles from combustion (especially vehicles); more likely to travel deep into the lungs due to smaller size and associated with chronic bronchitis and increased risk of lung cancer