What is an Urban Heat Island?
Just from the name of this term, make
a guess at what it means.
Write the answer in your green book.
Explain what this picture shows.
Improve your definition of Heat Island.
The term "heat island" refers to urban
air and surface temperatures that are
higher than nearby rural areas.
What factors can cause a Heat Island?
Brainstorm in your books.
Think about it!
Explain how these factors work to
promote a heat island.
Concrete and man made surfaces
Less water in the soil and environment
Excess energy from buildings
The principal reason for the nighttime
warming is that buildings block surface
heat from radiating into the relatively cold
night sky.
Tar, asphalt, brick and concrete absorb
insolation and release it as heat, rather than
reflecting it (without heat) like soil does.
During the day in rural areas, the solar
energy absorbed near the ground
evaporates water from the vegetation and
soil. Thus, causes evaporative cooling.
In cities, where there is less vegetation, the
buildings, streets and sidewalks absorb the
majority of solar energy input.
What about the buildings and the
people in them?
Make a list of the heat/pollution producing
activities that humans take part in that
would be more common in a city….
Remember, the way the heat island effect
works, is that it increases the overall
temperature of the city.
(a bit like greenhouse effect)
But in particular, it raises night time
temperatures (not always day time) by the
slow releasing of heat.
Which makes an overall increase
Design an experiment so that we
could measure if Hong Kong has a
heat island.
*Write on paper, be ready to present.
Individual work!
Also, an experiment to see if the
heat island is related to
urbanization.