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Introduction One of the keys to understanding weather and climate is learning about the difference in the way that water and land heats up and cools off. The purpose of this lab is to help you understand this difference. Directions 1. Set up the apparatus as instructed. The bottom of the bulb should be 10-15 cm above the top of the containers. Do not turn the light on yet. 2. One container should be half full of sand, and the other half full of water. The bulbs of the thermometers should be just below the surfaces of the sand and water. Make sure that the containers are equal distances from the light bulb. 3. On a separate sheet of paper, design a data table so that you can record the 21 temperatures for each container. Record the temperatures of both thermometers BEFORE the light is turned on. Record this on the data table in the space for “0” (zero) time. 4. Switch on the lamp and move it away from the containers because the lamp will continue to give off heat after it is turned off. Record both temperatures every 60 seconds for 10 minutes. 5. Shut off the light, and continue to record the temperatures every 60 seconds for another 10 minutes. 6. Obtain a piece of graph paper and design a graph to represent your two sets of data. Plot your data on the graph. Connect the points for the two sets of data. Label one line “water”, and the other “land”. FOLLOW-UP QUESTIONS 1. During your lab, which heated up the fastest? . . . the land (sand), or the water? Justify your answer by comparing the lines on your graph. . . .
2. Which cooled the fastest once the light was shut off? (Look at the graph again.) . . 3. There are four reasons why water warms more slowly than land. Try to come up with two. . . . 4. Air in the troposphere (bottom layer) is heated from the bottom up by heat given off by the surface. If the sun shines equally on Seattle (near water) and Bismarck, North Dakota (near center of continent), which would get hotter during the day? (Hint: Think about your lab.) Explain. . . . 5. Based on the results of your lab, which city would you would probably have a bigger difference between its day and night temperatures? . . 6. Anchorage (southern coast of Alaska) is several hundred miles north of Helena, Montana yet its January temperatures are similar to Helena’s. Explain why. . . 7. Most texts have maps that shows average January and July temperatures. Use the map in your text to find the coldest area in the Northern Hemisphere. Is it on land, or over water? . . 8. On the January map do the isotherms in the N. Hemisphere bend northward or southward as they go from ocean to land? This means that in the winter , areas over land are . . .Circle one: . . .warmer . . . colder 9. Which regions tend to have a greater difference between summer and winter temperatures? . . . areas close to oceans, or areas far from oceans? . 10.. What have you learned from doing this lab? . . .
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