STR Micro-Lesson: Melting Earth?
(click here to see the full image)
Question
This is the most common and versatile molecule on earth. In the form it is shown in above, it helps act as Earth’s thermostat, keeping the Earth from overheating. What is it?
Answer
The ice crystals above are viewed at 200x with a handheld digital microscope such as STR’s “Dlite Microscope”. Warmer Spring weather and longer days help melt snow in temperate climates, but in some places, the snow and ice never melts completely. These permanent sheets of snow and ice act like heat mirrors, reflecting energy from the sun back into space and helping to keep our planet cool. As areas of permanent ice get smaller, more of the suns energy is absorbed and temperatures rise. The measurement of reflected light energy is called Albedo.
Micro-Lesson* Plan
Topic: Energy – Global Warming
Download the enlarged version of the image above and show it to your class (using a projector or a color printout). Ask the question just below the image. You may wish to give hints.
Once you have elicited or presented the answer, explain that light from the sun warms surfaces at different rates. The ice crystals in the picture are very reflective with multiple, small exposed surfaces. Also make note of the lack of color in the image of the ice. Examine other surfaces in the room to compare texture and color and make predictions on how much light energy will be reflected or absorbed. If thermometers are available, students can test different surface temperatures by pointing a desk lamp at different objects in the room and measuring the temperature.
Experiment further by using a piece of white paper to simulate the large sheets of ice that exist at Earth’s north and south poles. Use a dark sheet of paper to simulate open water or a land mass. Shine a desk lamp (the sun) at each surface and measure the temperature of each (aquarium tape thermometers may work best). You can simulate melting ice by cutting or folding the paper to decrease the size and then measuring again. How does decreasing the ice area affect the surface temperature? These links may be helpful:
National Snow & Ice Data Center
Measuring Ice and Ocean Albedo Lesson Plan (PDF)
NASA lesson plan exploring Albedo
More…
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Comments?
Let us know what you think of this lesson idea, or if you have suggestions for more STR Micro-lessons.
*STR Micro-Lessons™ are designed as "plug-ins" to support and augment standards-based science teaching and learning. For complete lessons using the Scope on a Rope handheld digital microscope, see the STR Teacher Resources page.
