A term given to
urban areas because they are usually warmer
than surrounding
rural areas. An example of a heat island
is
Atlanta which is often dubbed 'hot'lanta'.
Causes of increased temperatures in cities are naturally due to
human activities.
Man-made materials such as concrete and metal
have a low
albedo, holding heat in much longer time period than
natural landscapes. In the evening, after the sun has set, these
man-made materials release
heat, and thus warm the air. Heat is also
generated by moving objects such as cars and trains.
The removal of natural
vegetation can also increase temperatures since
it provides shade. Vegetated areas also create a barrier preventing solar radiation
from heating the ground quickly and cools the air through the process of
evapotranspiration.