What is an Urban Heat Island?

1
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.

2
Explain what this picture shows. Improve your
definition of Heat Island.
3
The term "heat island" refers to urban air and
surface temperatures that are higher than nearby
rural areas.
4
What factors can cause a Heat Island?Brainstorm
in your books. Think about it!
5
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

6
Tar, asphalt, brick and concrete absorb
insolation and release it as heat, rather than
reflecting it (without heat) like soil does.

• The principal reason for the nighttime warming
  is that buildings block surface heat from
  radiating into the relatively cold night sky.

7

• 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.

8
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.

9
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
10
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.