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This section describes the surface properties of the earth and their reflectivity or albedo.
- water
- ice
- land
- meadow
- forest
- desert
Albedo: Introduction to Surfaces | Urban
Heat Island
Albedo: Introduction to Surfaces
 
Ice and clean snow surfaces have high albedos. Sea Ice in Lancaster
Sound in the Canadian Arctic.
Differences in surface characterisitcs t affect the amount of
radiation reflected from Earth's surface back to space. Ice and
clean snow surfaces have high albedos. A large percentage of solar
radiation (light and heat) is reflected. The greater the area covered
by continental ice sheets, the cooler the planet.
Oceans and plants have low albedo and absorb most of radiation
striking them. Increases in areas of ocean and vegetation lead
to decrease in planetary albedo and a warmer Earth.
Any surface receiving the suns ray's will absorb some of the energy
and reflect the rest. Some interesting effects of and consequences
for land use are shown below. See sections on ecosystems.
Source: Science and Impacts of Climate
Change CD -Presentation Graphics (2002) MSC Environment Canada/
ESS Natural Resources Canada, December
See Section 3.3.1 for more on Albedo
ACTIVITY 1
1. On a warm day put thermometers - for the
same length of time - on three cars whose colors range from light
to medium to dark. Record the temperatures. Repeat three tiimes
for each color. What is being measured ? Why are there differences
in the readings? What cost is saved by driving a light coloured
car? How is this knowledge useful in choosing clothing?
2. Repeat the experiment by placing thermometers
on natural vegetation, bare soil, concrete sidewalk, and asphalt.
Explain these results based on the light and heat energy.
Urban Heat Island
Below is a sketch of an Urban Heat-Island Profile. Notice that
this is graph is presented in Fahrenheit for late afternoon temperatures.
1 Celsius degree = 1.8 Fahrenheit degrees plus 32) are highest
in the downtown core, whereas the outer peripheries (rural areas)
have lower temperatures. 
ACTIVTY 2
- What is the range of temperature shown between
the downtown core and the outer peripheries (rural areas) in
Fahrenheit degrees? In Celsius degrees?
- List 5 reasons why the downtown or urban
core is warmer than the suburbs.
- Why would the late afternoon be the best
time to graph temperatures?
- How would this phenomenon affect gardeners?
Parks and Recreation departments?
The warming of urban air increases in intensity and area as cities
grow. This tends to increase the risk of more frequent heat waves. These
heat waves occasionally cause death, particularly among elderly
people, very young people and those who are ill in health. During
rainy seasons, this "heat island" increases the intensity
and frequency of rain showers, which creates a higher risk of flooding
or mudslides.
ACTIVTY 3 -Research
- Find examples of heat waves in Toronto or
Chicago where deaths due to heat wave have been documented. What
are the two basic reasons people die at this time?
- Jane Jacob's "Dark Times Ahead" cites
sociological studies that add an other major reason for these
deaths. What was discovered to be this additional factor?
ACTIVTY 4
- a) What is the range of albedos found in
this diagram?
b) Which surface absorbs the most heat? The least?
- Why is there a trend to "green roofs" HINT
7.4.???
- Which purchases should be influenced by
this diagram that are not labelled with albedo or reflectivity
ratings?
ACTIVTY 5- Research
- At what concentration\ of urban development
or population does the urban heat island effect begin?
Content Updated Sept 2005
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