1. ACTIVITY #11 Light Concentration and the Seasons.
Did you ever wonder why it is colder in the winter in Delaware and warmer in the summer?
What causes the seasons?
What effect will the angle of insolation have on the amount of energy a particular area receives?

2. GOALS: In this lab activity, you will … WD
Use a flashlight, protractor, and grid paper to do a mathematical analysis of decreasing energy values.

3. MAIN IDEAS: The important concepts and skills covered in this activity are … WD
The angle of insolation determines the amount of concentrated radiant energy an area receives from the Sun.
By decreasing the angle of insolation, there is a corresponding decrease in the amount of energy in a given area.

4. Light Concentration and the Seasons WD
Background: Some areas of our planet get more direct and concentrated sunlight during different times of the year.
As a result, these areas experience warmer periods we call summer.
When the Sun’s light is less concentrated and the days are shorter, these areas experience winter.

5. Light Concentration and the Seasons WD
In this activity, you will calculate the percentage of energy that is received from light transmitted at three different angles.

6. Purpose: WD
To determine how the percentage of light distributed (concentrated) in an area changes with a decreased angle of insolation.

7. Materials (per pair of students):
Flashlight
30 cm metric ruler
calculator
Protractor
90, 60, & 30 degree grid paper

8. Procedure:
Trace the area directly highlighted by the flashlight’s beam onto the graph paper.
If there is a brighter circle, surrounded by a somewhat dimmer circle, trace only the brightest part.
Part 1
Using a protractor, hold the flashlight over the 90 degree grid paper so it is at a distance of 20 cm.
Shade in the area that is circled on the grid paper.

9. Procedure: Count the number of grids that are shaded in:
(a grid more than ½ shaded counts as 1, a grid less than ½ counts as 0).