Differential Heating of the Earth

Name ______PS/ES Per.______Date______Mr. Landsman Differential Heating of the Earth

Background: Most of the energy from the sun reaches the earth in the form of visible light radiation. When radiant energy is absorbed by the earth’s surface, it changes into heat (longer wavelength than light). The earth’s heat re-radiates into the atmosphere. Gases in the atmosphere absorb some of this heat. In other words: THE SUN HEATS THE GROUND (or water), THEN THE GROUND (or water) HEATS THE AIR. The global wind and pressure belts result from differential heating of the earth on a global scale. Local winds result from differential heating due to local surface characteristics. This lab investigates the differential heating of the earth on a local scale.

Objective: To determine the heating and cooling characteristics of land vs. water.

Materials: Land, water, two clear cups, radiation source, two thermometers, data table, graph paper, ruler, colored pencils

Problem: A) Which material will increase in temperature more quickly? B) Which material will decrease in temperature more quickly? Procedure:

State your hypotheses here. ______

1. Create a data table where you will record temperatures in one-minute intervals for twenty minutes; Ten minutes with the lamp on, ten minutes with the lamp off. Provide a cell for time zero. The lamp will be turned off at the END OF THE 9th MINUTE. 2. Set up your experiment so that the only variable being tested is the difference in heating of land vs. water. Use the following checklist to help you. Include units.

Distance from light Land______Water______Mass of material Land______Water______Depth of thermometer Land______Water______Are the cups identical? ______Are the thermometers identical? ______

3. Sketch your experimental setup on clean white paper. Label all apparati and measurements. 4. Assign roles to group members so that the data gathering “run” goes smoothly.

Name______Role______Name ______Role______

1 Name ______Role______

4. Perform the experiment. Record data. Don’t forget to record data for time zero.

5. Graph your results on one set of axes. Use different colors for land and water plots. Label the DEPENDENT and INDEPENDENT variables as such. Include a title and key.

6. Answer the conclusion questions.

Conclusions: 1. In the boxes below, calculate the RATE of temperature change for each material with the lamp on and lamp off. Remember, the lamp was ON from time 0 to the end of minute 9.

Land Water

2 2. Do the results of the experiment support your hypothesis?______Briefly state the results of the experiment in terms of the variables tested. Cite your data. ______3. Describe the actions you took to ensure that the only experimental variables were the Land and Water. Indicate the significance of the CONTROL GROUP results. ______

3 ______4. Predict the rate (would it increase or decrease) of temperature change for sand that is wet. Explain your reasoning. ______

5. Predict the rate (would it increase or decrease) of temperature change for water that is muddy. Explain your reasoning. ______

4 ______