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Converting Solar Energy To Heat Energy

“The albedo effect” is a measurement of the amount of solar energy available to the Earth. When the sun shines on the earth, approximately 35% of the sun’s energy is reflected back into space, with 6% reflected by the atmosphere, 25% reflected by clouds, and 4% reflected by the earth’s surface.

Approximately 65% is absorbed by the earth, 15% by the atmosphere and 50% by the surface of the earth, including plants.

You have likely experienced the effects of solar energy when you have opened your car after it has been sitting in the sun during summer time. Solar energy enters through the windows. The ultraviolet rays (which cause sunburns) are screened out by the glass, but the rest of the energy goes through the glass. Of the energy entering through the car window, the infrared rays are absorbed by the atmosphere in the car as well as the metal, cloth and other materials of the car. What little remains of the reduced solar energy in the car is reflected back out to space through the windows. This is why cars with rolled up windows in the summertime are so hot when the door is opened. This is also why it is soooo dangerous to leave a child or pet inside a car with the windows closed, especially in the summertime

There are many factors that determine the ability of an item to reflect or to absorb energy from the sun. The activity which follows will give you an opportunity to investigate how solar energy is transferred to heat.

 

Activity:

This activity will allow you to observe how colors can affect heat transfer through the albedo percent of each color.

 

Materials:

  • Several sheets of colored paper
  • Scissors
  • Plastic wrap
  • Thermometer
  • Clear tape
  • Paper
  • Pencil
 
Safety concerns: Be sure to keep all heat, glassware, and sharp instrument safety rules. As with all science lab activities, the most important safety rule is to follow all teacher directions.
 

Procedure:

  1. Create boxes out of several different sheets of colored-paper.
  2. Tape a sheet of plastic wrap over the open end of each box.
  3. Punch a small hole (large enough for a thermometer) and insert the thermometer into the hole.
  4. Tape over any place on your boxes where heat might leak out.
  5. Place each of the boxes in sunlight for 15 minutes and record the temperature readings for each box every one minute. Write this information in the data tables provided.
  6. Graph your data.
 

Analysis:

  1. Which of the boxes had the highest final temperature?
  2. Which of the boxes had the lowest final temperature?
  3. Which of the boxes had the greatest increase in temperature over the shortest span of time?
  4. What relationship did you find between the color and the temperature of the box?
  5. Identify several variables that you could change to alter your results of this experiment.
  6. Besides aesthetic values, what are some important uses of color by humans?
 

Extension:

  1. Obtain several cups of different soils and compare the rate at which each warms and cools.
  2. Compare the heating and cooling rate of water with that of the heating and cooling rate of soil.
  3. Compare the heating and cooling rates of cement and asphalt, grass and sand, air and water, cotton and wool, nylon and cotton, etc.
 
Review science lab safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE Earth Systems Science core.

 


Updated October 24, 2008 by: Glen Westbroek

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