All of the questions please. Including the bonus. Thank you!
Sun angle and solar radiation (37 points)
Natural disasters such as hurricanes, thunderstorms, and tornadoes are ultimately caused by the Sun’s radiation. As the Sun’s energy strikes the Earth, the surface is heated. The rate at which the temperature of the surface increases (or decreases) depends on many factors including solar angle, daylight hours, cloud cover, and type of surface material (land versus water).
In this lab you will be examining the relationship between solar angle and solar radiation on the potential heating of the Earth’s surface. Many people mistakenly believe that the Earth gets warmer in the summer because our planet is closest to the sun at that time. However, during the
Northern Hemisphere’s summer, the Earth is actually at its farthest point
from the sun—around 3 million miles farther than during our winter.
Rather than distance, the variable that controls our seasonal changes is
the angle that the Sun’s rays strike the Earth called solar angle. Or, in
other words, the angle between the horizontal land surface and the
position of the sun. The diagram to the right illustrates solar angle. For land surface a person standing at the on the land surface, the sun would
appear elevated at a certain angle above the surface. This angle is the solar angle. Use a protractor and ruler as needed to help you answer the following questions.
1. What is the solar angle in the diagram to the upper right?
2. On the diagram below, use a protractor and ruler or other straightedge to help you draw arrows from the center of the sun to the land surface showing the following solar angles: 90°, 60°, 45°, 30°, 10°. Label each arrow with its correct angle.
land surface
3. Which of the solar angles above creates the most direct solar radiation to the Earth’s surface? Why?
4. Which of the solar angles above would result in the greatest surface heating (assuming all other variables that might impact heating are equal across the surface)?
Imagine the Sun’s energy is a 1 centimeter wide beam moving from the
Sun toward the Earth’s surface as illustrated in the diagram to the right.
In this example, the solar angle is 90°. If the Sun’s energy is moving
directly toward the surface, the surface area illuminated by the Sun will
be the same width as the Sun’s beam.
5. As solar angle decreases, the land area lit by the solar rays will be _____________ compared to a solar angle of 90°.
greater equal less
6a. Examine Sun A below. The line beneath the sun is the width of the sun’s beam. Draw one line representing the sun’s ray perpendicular to the beam width line from each edge of the line. These lines should intersect the land surface. Draw as precisely as possible ensuring an angle that is perpendicular (90°) to each end of the sun’s beam shown.
b. What is the solar angle for Sun A?
For the following, measure precisely to the nearest tenth of a centimeter.
c. What is the width of the beam in centimeters for Sun A?
d. What is the width of the illuminated area of this beam along the ground for Sun A?
A B
Using the data above, you can now calculate how much less intense the radiation striking the surface is compared to a 90° solar angle. The formula for this calculation is:
(Width of beam / width of illuminated area) * 100 = ______% of the maximum radiation intensity
7. Calculate the percentage of the maximum radiation received using your measurements from question 6.
The solar angle and percentage of the maximum radiation from Sun A (if drawn and measured correctly) represent what occurs at Century College on the summer solstice (June 21).
8a. Repeat the process now using Sun B. Draw one line representing the sun’s ray perpendicular to the beam width line from each edge of the line. These lines should intersect the land surface.
b. What is the solar angle for Sun B?
c. What is the width of the beam in centimeters for Sun B?
d. What is the width of the illuminated area of this beam along the ground for Sun B?
e. Calculate the percentage of the maximum radiation received using your measurements above.
The solar angle and percentage of the maximum radiation from Sun B (if drawn and measured correctly) represent what occurs at Century College on the winter solstice (December 21).
The previous examples illustrate the variable called beam spreading. As solar angle decreases, the same amount of solar radiation is spread over a larger land area.
9. There are several latitudes of significance related to solar radiation through the seasons. List the exact latitude of the following locations. Be sure to include whether the location is north or south of the equator. Check your answers with the instructor before continuing.
Tropic of Capricorn_________ Tropic of Cancer_________ equator_________
Arctic Circle _________ Antarctic Circle_________ Century College_________
10. Carefully plot and label these latitudes on the map on the next page. For all latitudes draw a line using a ruler in the correct location.
At the Tropics of Cancer and Capricorn solar angle varies between 43° and 90° over the course of the year. At the equator solar angle ranges between 66.5° and 90° during the year. At the Arctic and Antarctic Circles solar angle varies between 0° and 47° during the year.
11. On June 21 the direct rays of the sun are at 23.5° N. Put the latitudes below in order from highest (1) to lowest intensity of radiation on June 21 based on solar angle. If two locations receive the same intensity give them the same number. **Hint: You need to determine how close each location is to the latitude of the direct rays. The closer the location is, the higher its solar angle.
Tropic of Capricorn_________ Tropic of Cancer_________ equator_________
Arctic Circle _________ Antarctic Circle_________ Century College_________
12. The direct rays of the sun are at the equator on both equinoxes (March 21 and September 21). Put the latitudes below in order from highest (1) to lowest intensity of radiation on the equinox based on solar angle. If two locations receive the same intensity, give them the same number.
Tropic of Capricorn_________ Tropic of Cancer_________ equator_________
Arctic Circle _________ Antarctic Circle_________ Century College_________
Using the previous concepts, we can divide the Northern and Southern Hemispheres into three heating zones each: low latitudes (0° to 30°N or S), middle latitudes (30° to 60°N or S), and high latitudes (60° to 90°N or S).
13. Label “Low”, “Middle”, and “High” on the map on page 82 in the correct latitude belt in each hemisphere.
14. Hurricane formation requires a thick layer of very warm water near the ocean surface across a large area. Which latitudinal zone (low, middle, or high) is likely to be the spawning ground of hurricanes? Describe why hurricanes form in this latitude zone using the solar angle and beam spreading concepts.
15a. Severe thunderstorms and tornadoes require large landmasses with collision of contrasting temperature air masses. Place an “X” next to the latitudinal zone (listed below) where these weather systems most likely to occur.
b. Using the solar angle and beam spreading concepts, explain specifically why severe storms are unlikely to occur in each of the other zones not selected.
low latitudes:
middle latitudes:
high latitudes:
Bonus: This optional section may be completed for up to 5 extra points on this lab.
At some point in your life, you have probably noticed your shadow on a sunny day. Over the course of the day the length of your shadow changes. When is your shadow the smallest? When is your shadow the longest? Why?
You can use the shadow of an object to calculate the solar angle at any given location any day of the year. In this activity, you will be determining the maximum solar angle for today. The maximum solar angle occurs at noon (or 1pm during daylight savings time). This activity will work best if you have a partner to help.
a. Date of measurements:
b. Time of measurements:
c. Location of measurements:
d. Obtain a ruler or some other straight object. What is its length to the nearest tenth of a centimeter?
e. Place the object standing up at a right angle on the ground. What is the length of the shadow produced by the object?
f. Divide the length of the object by the length of its shadow and record.
g. To determine solar angle, take the inverse tangent (tan-1) of your answer to part 20f. Be sure that your calculator is in “degrees” not “radians”.
tan-1 (answer 20f) = solar angle
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