Urban Precipitation & Thunderstorms, Fog & Smog

convectional rainfall

UHI increases temperature, warm air cools, rises, condenses

relief rainfall

air is forced to cool when rising over buildings, condensing

impact

higher rainfall with impermeable surfaces means risk of flooding

sustainable drainage systems (SuDS)

green roofs, permeable pavements, rainwater harvesting systems, green spaces

cause of thunderstorms - pollution and dust

pollution particles act as condensation nuclei - water droplets form around tiny particles increasing cloud cover

cause of thunderstorms - UHI

rising, warm air and friction from buildings

sources for pollutants

vehicle exhausts and combustion

impacts of fog/pollutants

respiratory issues like asthma, CO2 emissions

what is smog

smoke particulates mixing with fog

London smog example

1940s, sinking of cold air trapping pollutants in pollution dome

photochemical smog

sunlight reacting with chemical pollutants, UV light causing them to break down into secondary, harmful chemicals