Central Arizona-Phoenix Long-Term Ecological Research Project
Title: Microclimates, Heat Islands & Shade
Author: Ecology Explorers Education Team
Time: 1 to 2 class periods
Grade Level: 6-12
Background:
The contour of the land, materials of land cover, the presence or absence of plants,
moisture and time of day may result in many climates (microclimates) within one
ecosystem. The urban heat island is one way in which people affect the local climate
in their urban ecosystem. Currently, during the summer, Phoenix experiences nighttime
temperatures that are 12oF warmer than the surrounding rural areas. The heat island
occurs after sundown as large heat absorption during the day by cement, asphalt and
other parts of the built environment is slowly released back to the atmosphere during
the night.
Scientists collect temperature data from weather stations across the Phoenix
metropolitan area, but even within your schoolyard, your students can compare
temperatures to test whether different materials or plants are making part of the
schoolyard hotter or cooler. For example, “shading and evapotranspiration (the
process by which a plant actively moves and releases water vapor) from trees can
reduce surrounding air temperatures as much as 9° F (5°C). Because cool air settles
near the ground, air temperatures directly under trees can be as much as 25°F (14°C)
cooler than air temperatures above nearby blacktop.” (http://www.eere.energy.gov
Sep. 11, 2006).
Why study microclimates?
• Temperature has an impact on the kinds of plants and animals that
can live in a particular place
• Varying types of land cover can affect temperature
• The temperature can affect comfort levels of people, in turn affecting how
much energy is used to keep people cool or warm.
What kinds of scientific investigations can be developed from this activity?
Students can compare data taken:
• on different ground covers (grass, sand, concrete, gravel, etc),
• at different times of the day,
• at different times of year
• at different types of shade (buildings, directly under a tree, shadow of a tree
etc).
This activity is divided into two parts. The first part suggests a procedure for creating a
long-term data base of temperatures associated with various ground covers in your
schoolyard. The second part suggests possible research questions for students to
investigate the affects of shade on various surfaces and around various objects (natural
and man-made). The best condition for conducting these experiments is on sunny
calm days. On windy days the air temperature may be uniform because the wind
mixes the air.
This lesson was written using the metric system, but you may decide to use feet and
Farenheit measurements for temperature as these may be more meaningful for your
students.
Vocabulary:
Urban Heat Island (UHI) effect –“a nighttime phenomenon where temperatures in
urbanized areas are higher than in the surrounding rural areas. Minimum
temperatures in metropolitan Phoenix's urban areas are about 12o Fahrenheit (~6oC)
more than those in the outlying rural areas.
Microclimate- local conditions of air and soil temperature, humidity, and wind
speed, vary due to local differences in topography, light absorption and reflection,
and air pollution.
Thermal Conductivity- the amount of time it takes to transfer heat through an object
Thermometer- used to measure temperature. There are digital, mercury-filled, and
spirit-filled thermometers. Easiest to read and use are the digital thermometers
although they can be less accurate and cost more.
Objective(s):
• The student will be able to compare the land cover, shade and temperatures, in
different microclimates to begin to explain how this impacts both people and other
organisms.
• The students will be able to record temperature readings and detailed observations
while exploring microclimates.
Standards: Only looking at grades 5-12 Arizona State Science standards
• The standards listed are those the activity meets without doing any extensions or the
activity as part of a larger unit. Many more standards can be met with the extension
suggestions.
S1-C1-GR5-8-Observations, Questions, and Hypotheses: Formulate predictions,
questions, or hypotheses based on observations. Locate appropriate resources.
S1-C2-GR5-8-Scientific Testing (Investigating and Modeling): Design and conduct
controlled investigations.
S1-C3-GR5-8 Analysis and Conclusions: Analyze and interpret data to explain
correlations and results; formulate new questions
S1-C4-GR5-8 Communication: Communicate results of investigations
S1-C1-GRHS- Observations, Questions, and Hypotheses: Formulate predictions,
questions, or hypotheses based on observations. Evaluate appropriate resources
S1-C2-GRHS- Scientific Testing (Investigating and Modeling): Design and conduct
controlled investigations.
2
S1-C3-GRHS-Analysis, Conclusions, and Refinements: Evaluate experimental design,
analyze data to explain results and to propose further investigations.
S1-C4-GRHS-Communication: Communicate results of investigations.
S3-C1-GR5-PO2 Propose a solution, resource or product that addresses a specific
human, animal, or habitat need.
S3-C1-GRHS-PO4 Evaluate the following factors that affect the quality fo the
environment: urban development
Materials:
•
Thermometer (one per plot)
**Teacher note about thermometers: Calibrate the thermometers. Place
all the thermometers into a beaker of ice water for 5 minutes. The
thermometers should read between 0oC to 0.5oC. Choose one
thermometer that is correct and label it the “thermometer of excellence”
(TOE). Make a note of how each thermometer differs from the TOE and
record on you data sheet. When you compare your data you will need to
add or subtract this amount from your thermometer readings.
•
Scale map of schoolyard (If available) or go to http://maps.google.com (or
other mapping website) to get an aerial photo of the area
Data Recording Sheets
•
•
•
“A Shady Situation” from Chain Reaction 4: Urban Ecology, the article and
PDF file can be found at http://chainreaction.asu.edu/ecology/digin/shady.htm
Experimental Design Data Sheet
Safety Precautions
• Make sure where you are gathering data is in a safe environment (i.e. you do
not have to worry about cars running over you or trees falling on you.)
• Thermometers should be mercury free. They are cheaper and safer if they
accidentally break.
Suggested Procedure:
1. Discuss with your students that they are going to explore microclimates in their
schoolyard. You might ask what they think a microclimate is and why they think it
matters to them. Have the student read a “Shady Situation” in ASU’s Chain Reaction 4:
Urban Ecology. Have they noticed which parking lots have trees? What are some
microclimates the students may have encountered traveling to school or in the
schoolyard (i.e. pavement, grass)?
3
2. Define the boundaries of your study area. Have the students look at a scale drawing
or aerial photograph of their schoolyard (or take them out to the study area). Have the
students predict which surfaces will be hottest and coolest. Record their predictions.
For older students, you may which to have several different study areas.
3. As a class decide on three to five different ground cover (grass, concrete, soil, sand,
gravel, etc) points to compare. Make sure to record these locations on your map. If
you don’t have a scale map or aerial photograph, have the students draw a rough
sketch of the area and record the location of these points. (teacher note: you may
wish to have the students view the short video clip man-made materials and the heat
island at http://asusmart.com/blog/news/smart-on-channel-3 )
4. Select one point for your standard schoolyard air measurement. This point should be
at least 2 meters (6.5 ft) away from a building and over gravel. If you don’t have gravel
you can use grass, dirt or concrete and make sure to note this on your data sheet). The
standard temperature measurement should be taken at a height of 1.35meters (4.4 ft)
with an aluminum foil “skirt” around the thermometer bulb to shade it from the sun.
5. Have the students take temperature measurements at each of the different ground
covers and at the “standard” temperature site. Student should lay their thermometers
directly on the surfaces (grass, concrete, etc.). Make sure the student taking the
schoolyard standard measurement does not touch the bulb with his/her fingers. Have
the students record the temperatures after 5 minutes. Record these temperatures on
the class data sheet.
6. On the data sheet record the difference between each of the data points and the
standard (groundcover – standard). This number will give you how much higher ( a
positive number) or lower (a negative number) the ground cover is in relation to the
average temperature (the standard measurement) for your schoolyard.
7. Have your students record the “official” Phoenix (or your city’s) temperature taken at
approximately the same time (this is available from any weather website). You may
have to convert this to oC.
8. Have the students complete the questions on the worksheet.
9. Continue to collect data from these same locations throughout the day or the year
to see daily or seasonal changes temperatures.
10. Shade Comparison. In “A Shady Situation”, the scientist measured the surface
temperatures around each tree at several distances from the trunk. She recorded the
different surfaces at each of these distances. She also measured in each direction (N,
S, E. & W) Based on your earlier measurements, what differences would there be
among surface temperatures of different ground cover areas shaded by a tree? Do
the surface temperatures change as you move from directly beneath a tree to the end
of the tree’s shadow? Is there a temperature difference between shade from a
4
building (blue shade) or from a tree (green shade) on the same type of surface? Have
your students develop testable hypotheses about these or other “shady” questions and
design experiments to test their predictions. What patterns did they find? If they were
to design their schoolyard would they add more trees or more shade structures? Why or
why not?
Evaluation:
• Student completes data sheet with detailed observations and accurate
temperature readings.
• Students complete the questions on the student handout. These answers should
reflect some understanding that the landscape around the thermometer will affect
the temperature it records and that some surfaces retain more heat than others.
• Students should design and conduct a study of shade and temperature.
Extensions:
• Students can
o Go back and visit plots to look for changes in plants and animals (or signs of
animals)
o Test for humidity, wind speed, measure canopy cover,.
• Have students take multiple temperatures in their study area and create a thermal
map with isotherms (http://cimss.ssec.wisc.edu/wxwise/contour/Learncon.htm).
• Thermal Activity adapted from Cold ‘n Hot activity (VanCleave, p. 126).
•
o
Students should be able to familiarize themselves with basic thermal principles.
Before beginning the lesson have samples of different types of materials, plastic,
different types of materials (plastic, concrete, rubber…). Place the different types of
materials under the light source at the same time. Check the temperature of the
objects and record. Use the next thirty minutes to begin the activity to talk about
microclimates. After ten minutes, come back to the materials. You can use
thermometers to check surface temperature or you could experiment with ice
melting to see if there is a difference (the thermal conductivity will affect the melting
rate).
o
After approximately thirty minutes students will then check the temperature of the
different objects. Record the temperature. Now take the objects out of the light for
another thirty minutes.
o
Record the temperature under shade at ten minutes intervals for thirty minutes. Did
you notice any differences in heating amounts of ability to cool?
Download a copy of outcomes (outdoor human thermal comfort export
system). Let students plug in their data and change variables to see how
they can change the surroundings to be more comfortable to humans (ie.
change the materials around them, change the clothing they are wearing).
http://www.fs.fed.us/ne/syracuse/Tools/tools.htm
5
Resources
Regional climate information
http://met-www.cit.cornell.edu/other_rcc.html
http://www.wunderground.com
Heat index Conversion
heat index http://www.srh.noaa.gov/elp/wxcalc/heatindex.html
Heat Index Table http://www.nws.noaa.gov/om/heat/index.shtml
Urban Heat island graphics of Phoenix Arizona
http://dcdc.asu.edu/swipatlas/
http://caplter.asu.edu/home/capltertour/heat_island.htm
Heat Island video (interview fo ASU scientist on newschannel 3)
http://asusmart.com/blog/news/smart-on-channel-3
Akbari H, Davis S, Dorsano S, Huang J, Winnett S (1992). Cooling Our Communities: A
Guidebook on Tree Planting and Light-Colored Surfacing. U.S. Environmental Protection
Agency, Office of Policy Analysis, Climate Change Division. Lawrence Berkeley National
Laboratory Report No. LBL-31587.
Akbari H, Rosenfeld A, Taha H. (Feb.1990) Summer heat islands, urban trees, and white
surfaces. Proceedings of American Society of Heating, Refrigeration, and Air
Conditioning Engineers.10-14,. Atlanta, GA: American Society of Heating, Refrigeration,
and Air Conditioning Engineers. Also published as Lawrence Berkeley National
Laboratory Report LBL-28308.
Höppe, P. (1999) The physiological equivalent temperature - a universal index for the
biometeorological assessment of the thermal environment. International Journal Of
Biometeorology 43 (2) p.71-75.
Oke, Thomas. (2004). Sitting and Exposure of Meterological Instruments at Urban Sites.
27th NATO/CCMS International Technical Meeting on Air Pollution Modelling and its
Application, Banff, 25-29 October, 2004.
Patel, Tera (1995). Parisians Pale but Stay Warm. New Scientist 148 p. 10
VanCleave, Janice. (1991). Earth Science for Every Kid. John Wiley & Sons: New York
6
Climate Data Sheet: Groundcover in the Schoolyard If you use oF, please note this on the data sheet School: _____________________________________________________ Date:______________ Time: ___________ Official City Temp.(oC) ________________ Latitude/Longitude (if known)___________________________________ Standard Temperature (oC): ___________________ (taken at 1.35 m over gravel, at least 2 meters away from a building) Location of standard temperature measurement (please describe in detail so another person can find the same spot, also note if it is over something other than gravel) or mark it on a map: ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________ Study Site: please describe in detail so another person can find this study site ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________ You may not have all of the different types of ground cover at your school, test for those you do have and write NA (not applicable) for the others. Ground Grass cover Temperature ◦C at ground level Difference from Standard Gravel Soil Sidewalk Blacktop Sand (concrete) (asphalt) Woodchips
(Groundcover – Standard) Mark the location of where each temperature measurement was taken on a map or sketch of the study site so you can continue to take measurements at the same location 7
Questions for Ground Cover Study:
1. Which ground cover did you predict would be the hottest?
2. Which ground cover did you predict would be coolest?
3. Which ground cover was hottest?
4. Which ground cover was coolest?
5. Give one possible explanation for why one ground cover is hotter than another.
6. Where would you like to stand if you were waiting for a bus? Why?
8
7. Is your standard schoolyard temperature higher or lower than the official Phoenix (or
your city’s) temperature?
8. How do you think the surface temperatures you recorded in your study area affect
your standard schoolyard temperature?
9. How do you think the local surroundings affect the temperatures recorded by the
official weather stations?
9
Rubric for Shade Investigation
Students should complete a laboratory report after completing their shade
investigation. The following is a possible rubric for a lab report consisting of: Heading,
Introduction, Procedure, Results, and Conclusion for a total of 10 points.
___ Heading- 1 pt.
A few words describing what was done or found
___Introduction- 2 pts.
Why is what you studied important? What was the question?
___Procedure- 2pts.
How did you collect your data, description of the site (location, date, time, weather
conditions?)
___Results-2 pts.
What was found in the study, presence of at least one table or graph (with written
explanation).
___ Conclusion- 2 pts.
Summary of what was found and the implications or why anyone should care what was
found. Did the data answer your question? Ideas for further research.
___ Mechanics- 1 pt.
Grammar, spelling
Major questions to consider in conclusion: What are some positive and negative
aspects of humans on the environment (humans, plants, and animals), for the negative
aspects what are some possible solutions?
10
Name(s)___________________________
Designing your Investigation
Question:_____________________________________________________________
________________________________________________________________________
Write your hypothesis and prediction:
Write an alternative hypothesis and prediction:
Method: Write down your method in detail so that someone who is not in your group
could follow your method exactly the way you would.
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
11
Use another sheet of paper to record and analyze the data and write your conclusions.
12