Angle of Insolation Lab Page of 5 1

Name: Period: Date: EN

ANGLE OF INSOLATION LAB Prelab: Read through the lab and answer the following.

1. What are the two variables in this experiment?

a. __________________________________________________________________________ b. __________________________________________________________________________

2. Which is the dependent variable?

3. Which is the independent variable?

4. Identify two factors you will keep constant.

a. __________________________________________________________________________

b. __________________________________________________________________________ 5. The different angles of the thermometers represent different spots on Earth and the angle of

incoming solar radiation. Which angle in the lab is closest to representing the equator?

______________________________________________________________________________ 6. Which angle in the lab is closest to representing the poles?

_______________________________________________________________________________

7. Write a hypothesis about what you think will happen in this lab.

_______________________________________________________________________________

_______________________________________________________________________________ Materials

• Insolation Table • 3 angled wooden block • 4 thermometers

• 100W light bulb • stopwatch • ruler

Safety:

1. Don’t touch the light bulb after it has been on. It will be hot.

2. Take care when plugging and unplugging the insolation table.

3. Avoid looking directly at the light bulb. Procedure:

1. Identify the 30, 60, and 90 degree wooden blocks at your lab station as shown in the diagram to the right.

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2. Positions the blocks and the thermometers as shown in the diagram below, placing each thermometer at a distance approximately 12cm away from the light bulb. You may need to use tape to keep the thermometers in place.

3. Record the starting temperature of each

thermometer to the nearest degree in the “start” column in Table 1.

4. Plug in the insolation table. The light bulb

should light.

5. Observe and record the temperature for each thermometer to the nearest degree one minute after plugging in the insolation table. Record these measurements in the one minute column in Table 1. Continue timing and recording temperature at one-minute intervals for five minutes. Record all temperature measurements in Table 1.

6. Unplug the insolation table. Remove the thermometers from the blocks. Place at a distance

from the light bulb to allow thermometer readings to return to room temperature or close to it. Allow the thermometers to stand at room temperature for 5 minutes.

7. Repeat steps 2-6 recording data in Table 2.

8. Repeat steps 2-6 recording data in Table 3.

9. Using data from Tables 1, 2, and 3, calculate average temperatures for each angle of

insolation at the start and for minutes 1 through 5. Record your average calculations in the appropriate space in Table 4.

10. Obtain a sheet of graph paper from your teacher or using a graphing program such as Excel,

graph your data from Table 4. Data Tables Table 1

Start 1 min 2 min 3 min 4 min 5 min

0° angle

30° angle

60° angle

90° angle

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Table 2 Start 1 min 2 min 3 min 4 min 5 min

0° angle

30° angle

60° angle

90° angle

Table 3

Start 1 min 2 min 3 min 4 min 5 min

0° angle

30° angle

60° angle

90° angle

Table 4

Start 1 min 2 min 3 min 4 min 5 min

0° angle

30° angle

60° angle

90° angle

Conclusion Questions: Our seasons are caused by the changing angle of the sun in the sky. In the lab today you investigated how the heat energy absorbed from a source of radiation depends on the angle at which it strikes. This lab is a model of insolation (sunlight) received at three different latitudes on the Earth. The 90° thermometer represents a place near the equator and the 30° thermometer represents a high latitude location.

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1. Which thermometer angle represents a place where the sun is highest in the sky?

2. Describe the relationship between angle of insolation and the temperature. Look at your data tables!

3. Which one of the thermometers best represented the Poles? Explain why.

The diagram below shows that when the sun is high in the sky, the rays of sunlight are concentrated into a small area on the surface of the Earth. When the Sun is low, insolation is spread over a large area and insolation cannot heat the Earth as quickly.

4. What happens to the intensity of insolation as the angle of insolation increases? Explain why this happens.

5. Why is the sunlight always weak at Earth’s poles?

6. As your latitude increases what generally happens to the angle of insolation?

The three dimensional graph to the right shows us the amount of insolation at different times of the year in different spots on Earth’s surface. Use this graph to answer the next three questions.

7. In what month does the North Pole receive the maximum insolation?

8. Where on Earth is the strength of insolation nearly constant throughout the year?

9. In what month does the South Pole receive the maximum insolation?

10. Why is sunlight stronger when the sun is directly overhead?

11. What three factors determine the angle of insolation at any location on Earth?

12. What is insolation?