TOPICS:  Heat transfer, microclimates

LEVEL:  Middle and high school

TIME:  This activity can be done as a class on school grounds or assigned as a homework project.  Allow enough time for students to have film developed, pictures mounted, and so on.

ADVANCE PREPARATION:  Collect old ski or other outdoor magazines for class use. You may wish to take photographs yourself to illustrate the answers to the discussion questions.  Student displays which are particularly well done can be saved and added to your collection .

PREDICTIONS: In class discussion, encourage creative, logical, and critical thinking. We recommend that you introduce the following ideas if they are not suggested by students:  Warm sports are typically found next to buildings, trees, water, dark objects, and other heat sources.  The ground is a heat source in winter; frost spots are typically found on objects not in good thermal contact with the ground, such as automobiles, bridges, tree twigs, grass, and windows.

QUESTIONS 2-10 require higher-order thinking skills.  We recommend that you discuss these questions in class prior to having students write out their answers .

2. Dark-colored objects absorb more sunlight are, therefore, warmer.  Light colored objects reflect more sunlight, and are cooler .

3. The dark-colored bark absorbs more heat than the snow. Radiation of heat from the bark then melts or sublimates the snow near it.  Evergreens may have a larger snow depression because the needles catch the snow as it falls .

4. Due to the position of the sun in winter, warm spots usually are south-facing.  They receive more of the sun's rays .

5. The sun, being low in the sky in winter, will not shine on the north-facing side.  Therefore, snow melts there last .

6. Evidence could include observations such as melting from roof, melting near foundation of house, no first frost formation, etc .

7. The presence of many large icicles indicates poor insulation in the roof .

8. A dark-colored substance, such as dirt, absorbs more sunlight and the snow around it melts faster than clean white snow.  Freshly fallen snow has a reflectivety (albedo) of up to 90%; the albedo of dirty snow is considerably less .

9.  Water has a higher specific heat than rocks and soil, so more heat is stored per unit mass.  In addition, a larger volume of water is heated during the summer, which is slowly released in autumn and winter .

10. The ground is a good source of heat in the winter environment.