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Significance: Sunlight makes a huge impact on temperature. In the photo below, University of the Nations students J. H. Kim of Korea (left) and Becky Akhahoya of Kenya use an infrared thermometer to measure the temperature of a building's roof at Hawaii's Mauna Loa Observatory. They found that the temperature of the roof was much hotter than that of the lava at this remote site 3,400 meters (11,200 feet) above sea level.
 Click to view enlarged version.
Photograph by Forrest M. Mims III.
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Supplies Needed:
You can do simple heat island studies with a conventional or digital thermometer. For more detailed heat island studies, a non-contact infrared thermometer is best.
1. Conventional Thermometer. Liquid thermometers feature a colored fluid in a thin capillary running through a glass rod (the stem). The fluid expands when warmed, and the length of the column of fluid represents the temperature. Many different kinds of thermometers are available from retail stores and online science suppliers. Select an inexpensive, non-mercury, liquid thermometer for best results.
Some conventional liquid-filled thermometers have a temperature scale marked or etched directly on their glass stem. Others are mounted on a plastic or metal backboard on which a scale is printed. Often a Celsius scale will be on one side of the stem and a Fahrenheit scale on the other side.
When using a conventional thermometer to measure temperature islands, keep the thermometer's bulb (the end of the thermometer closest to the lowest temperature on its scale) shielded from direct sunlight and skylight. When the thermometer is not mounted on a backboard, this can be done by making a small hole in the bottom of a white paper or foamed plastic cup through which the bulb end of the thermometer is inserted. You can also use white paper rolled into a small cone. The thermometer is inserted into the apex of the of the cone until the bulb is shielded. Tape the end of the cone to the shaft of the thermometer. Modify this procedure to shield the bulb of a thermometer mounted on a backboard.
Always keep a thermometer in a protective case to avoid breaking it. Never carry a glass thermometer in a pocket. it might break!. Caution: Mercury thermometers will release mercury when broken. Avoid using them!
2. Digital Thermometer. A digital thermometer features an electronic readout that indicates the temperature. Most allow you to select either the Fahrenheit or Celsius scale. Many include a remote temperature probe connected to the readout by a thin, flexible cable. These are usually known as indoor-outdoor thermometers, and they are well suited for heat island studies and experiments. Many different kinds of digital thermometers are available from retail stores and online science suppliers. Use one of the methods described above to shield the probe of a digital thermometer from direct sunlight.
3. Non-Contact Infrared (IR) Thermometer. This is an electronic thermometer that uses a pair of heat sensors installed inside a plastic housing to measure the temperature of objects from a distance. One sensor is shielded, and the second is exposed through a small hole in the housing to the object whose temperature is being measured. Many different kinds of IR thermometers are available from industrial suppliers and online dealers. One of the least expensive at the time this project was prepared was the Actron CP7875 PocketTherm Infra Thermometer. You can find many IR thermometers by searching the web.
Some infrared thermometers are equipped with an internal laser aiming device that projects a bright point of light on the object whose temperature is being measured. Caution: When using an IR thermometer equipped with a laser, switch the laser off if possible. When using the IR thermometer with the laser switched on, never point the laser at anyone or at a shiny surface. Never point the laser beam at your eyes!
Always keep an infrared (IR) thermometer in a protective case to protect it from dust and to keep from scratching its readout. If it did not come with a case, store it in a clean sock.
An IR thermometer is operated simply by pointing it at anything whose temperature is to be measured. Press the power button to activate the thermometer. Various IR thermometers have different operating controls, so be sure to read the instrument's instructions. Most IR thermometers have a "hold" mode. This allows you to point the thermometer at an object, measure its temperature and read the temperature when it is convenient.
Test the IR thermometer by pointing it at your hand, your clothing, a book and a light bulb, and notice the temperature differences. Next, point the IR thermometer at the floor and then at the ceiling. Warm air is lighter and rises. Thus, the ceiling will usually be warmer than the floor.
4. Notebook or Spreadsheet. Pencil or pen and notebook or, alternatively, a clip board with a spreadsheet arranged like this: |
NAME: |
DATE: |
SKY CONDITION: |
If you plan to measure temperature over more than one day, use a spreadsheet like this:
DATE |
TIME |
OBJECT |
TEMPERATURE |
SKY CONDITION (SUN EXPOSURE, CLOUDS, ETC.) |
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Note: Mention of commercial products and suppliers does not imply that they are endorsed by NASA or the author. You can find many sources for conventional and IR thermometers at retail stores and by searching the web.
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