 Sustainable
Urban Design and Climate
WHAT CITIES DO TO THE LOCAL CLIMATE
There is considerable concern about the possiblity of world climate change
due to the enhance greenhouse effect. Scientists have predicted global
temperature rises of between 1 and 3.5 degrees Celsius by the year 2100.
Yet temperature rises of about the same size have already
occurred in some big cities, simply because the city is there! Particularly
at night, cities are usually warmer than their rural surroundings, because
of heat stored in bricks and concrete and trapped between close-packed
buildings - the so-called urban heat island effect. Have a look at how
temperatures across Melbourne are affected
by land-use. City wind speeds are lighter, on average, and vary from place
to place. Wind "tunnels" and "hot-spots" occur
where winds are channelled down city streets or wash down the faces of
tall buildings. By contrast, streets running perpendicular to the wind
direction are sheltered, to the extent that pollutants may not disperse.
Paved surfaces mean that runoff from rainfall reaches a higher peak flow
in urban areas, and reaches it much faster. As the city grows, the climate
changes intensify.
Continue with the next topic: WHAT
CITY CLIMATES DO TO PEOPLE.
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