urban climate Flashcards
UHI effects
urban heat island
a city centre can be over 10 degrees warmer
causes of UHI
- radiation reflected from walls
- buildings store solar heat
- lack of vegetation
- traffic
- antrhopogenic heat from buildings
- tall buildings trapped air
precipitation development
- UHI increase convection leading to showers
- uplift cuases low pressure and draws moist air into the city
- urban areas recieve 10% more frequent cloud cover
- pollutants act as condensation nuclei
winds development
buidlings create frictional drag on air
- high rise buildings channel winds into canyons where speed increases
- winds can be drawn from surrounding areas
- air is pushed around up over buildings
air quality - fog
- cities in LIC experience mor fogs from industrialisation and car use
- hazardous to health with pollutants
air quality - particulate pollution
suspended particulate matter - solid matter from pollution sources
sulphur dioxide - haze, acid rain, respitory problems
carbon monoxide - heart, fatigue and headache
air quality - photochemical oxidants
- smog, headaches, irritated eyes, chest pain
- react with sunlight and produces ozone
- conditions worse in winter
air quality example
LA
- high numbers of cars
- frequent sunshine
- topography
all trap pollutants at low levels
managing air quality - clean air acts
1956 - smoke free zones in UK urban areas
1990s - regulation imposed of airbourne pollution
councils required to monitor pollution and establish management
managing air quality - vehicle control
- london has congestion charge and low emission zone
- pedetrianised cities
- athens: 2.5k of city is traffic free
managing air quality - public transport
- manchester developed a tram system, bus only lanes, park and ride schemes
- vehicle emission legislation: manufacturers develop more efficient fuel burning engines
- electric cars from 2030
