Lesson Two (ELEMENTARY)

THE URBAN HEAT ISLAND EFFECT

Concept:

An urban heat island is the result of replacing local vegetation with dark, heat absorbing surfaces. The associated increase in summertime temperatures increases the use of energy for air conditioning and affects the level of air pollution.

Lesson Two Goal:

Students will learn about "urban heat islands", the effects of urban surfaces on urban heat islands, and effects of urban heat islands on energy consumption and air quality.

Utah State Science Core Objectives:

5^th grade: 3050-02

6^th grade: 3060-0101

Intended Learning Outcomes:

Materials/Preparation:

Vocabulary Words:

Reflection, absorption, impervious, pervious, urban heat island, surface temperature, surrounding air temperature, rooftop garden, energy, consumption, asphalt, concrete

Background Information:

1. Surface color:
   1. Dark colors absorb solar radiation.
   2. Light colors reflect solar radiation.
2. Vegetative surfaces:
   1. Vegetated areas are cooler than non-vegetated areas.
   2. Rooftop gardens are cooler than dark-colored roofs.
   3. Areas shaded by plants may be cooler than areas shaded by buildings.
3. Surface permeability:
   1. Impervious surfaces prohibit water penetration e.g., asphalt and concrete surfaces and roofs.
   2. Pervious surfaces allow water penetration e.g., gravel, soil, grass, and other plant cover.
4. Relationship between surface temperature and surrounding air temperature:
   1. Surface temperatures affect surrounding air temperature
   2. Hot surface temperatures increase the surrounding air temperature
   3. Cool surface temperatures decrease the surrounding air temperature
5. Reduction of urban heat island effects:
   The use of light colored surfaces helps reduce urban heat island effects as follows:
1. Light colored roofs and hard surfaces cool the surrounding air.
2. Decrease in surrounding air temperature slows the rate of ground-layer ozone formation.
3. Decrease in surrounding air temperature decreases the amount of energy used for air conditioning
   1. Lower energy use decreases the need for power generation.
   2. Less power generated decreases the amount of carbon dioxide released into the environment.
6. Urban vs. suburban temperatures
   Temperatures in the urban environment can be 8 degrees Fahrenheit hotter than the suburban or rural surroundings.
   
7. Brief on pollutants: see Lesson 3 for more detail
   1. CO₂ is one of the products released during the burning of fossil fuels.
   2. Ground-layer ozone is one of the products formed following a long chain of chemical reactions involving car emissions. Formation of this ozone increases with increases in temperature.

Instructional Procedures:

1. Review the scientific process of formulating a question (hypothesis), collecting data through experimentation and observation, and finally explaining the results of the test. Show the houses with the two different types of roofing materials provided in the Kool Kids box. Ask the students to write down a hypothesis as to whether there may be differences in temperature between the two surfaces when exposed to similar environmental conditions. Also ask whether there may be an effect of the materials on the temperature of the roof, or the inside and outside area of the houses.
2. Assist the students in setting up the experiments to test their hypotheses. Students may want to work in small groups or pairs to do this set of experiments. Take the houses outside and place them in direct sun about five feet apart. Put a thermometer near each house and place the attached thermal lead inside the house. Cover the actual thermometer so it is not exposed to direct sun. Allow the houses to remain in direct sun for at least 10 minutes, then have students record (on copies of the sheet provided) the following temperatures: roof surface (taken from the Heat Spy Gun), inside the houses (taken from the thermometer leads [switched to "outside"]), and outside the houses (taken from the thermometer [switched to "inside"]). Repeat the experiments above, however, expose the houses to full shade (e.g., behind a building) or dappled light (e.g., under tree with a fairly open canopy). Encourage students to come up with other variables that can be tested (e.g., amount of time in sun or shade).
3. As a class, interpret and discuss the data collected. Discuss how the differences in temperature between the two houses may affect energy use for air conditioning.
4. Show overheads in the Lesson Two packet. Discuss the urban heat island effect, why we want to reduce heat island effects, and how to cool our communities. Have students discuss whether surface types found in their neighborhoods contribute to a local heat island effect.
5. If time permits, show the thermal image in the Lesson One packet that shows urban elements labeled on the map. Discuss the surface types used for the roofs of the Delta Center (white) and the Matheson Courthouse (black). Compare the thermal images of both.

Assignment:

Have the students write a paragraph in their science journals on one of the following ideas:

1. Summarize the experiment.
2. Advocate one type of roofing material over the others, giving several supporting reasons why it was chosen.
3. Identify and discuss other experiments they could set up to explore more about the urban heat island topic.

Title of Experiment:

Problem:

Hypothesis:

Procedures:

Observations:

Conclusion: