URBAN MICROCLIMATES
Construction of cities lead to: Profound changes in the climate of a specific locality
What do cities do? They destroy the existing microclimate and create new ones. There are three processes involved: 1. production of heat 2. alteration of land surface 3. modification of the atmosphere
PRODUCTION OF HEAT Combustion of fuels Release of heat stored in city’s brickwork and concrete Creation of ‘urban heat island’
Altlanta urban heat island
Urban heat profile
Another urban heat profile!
Urban temperature transect
ALTERATION OF LAND SURFACE Buildings and streets can change wind speeds
Other urban variables to consider:
Wind velocities can vary very locally in urban areas
Wind velocities can be increased!
MODIFICATION OF THE ATMOSPHERE Air pollution reduces sunlight Development of smog Calm conditions with descending air and warm pollutants rising create an inversion layer.
Los Angeles inversion layer
Increase in condensation nuclei leading to fog