Name:
Per.:
Date:
Seasonal Energy Flux on Earth
Objectives
(1) Describe seasonal changes in radiation for Earth and the reasons for these
changes.
(2) Explain how clouds can influence Earth’s net energy balance.
Background Information
Earth’s Energy Budget
One way to understand Earth’s climate is to consider Earth’s “ENERGY BUDGET”.
Energy enters the Earth system from the sun in the form of radiation in visible light and
ultraviolet wavelengths. This energy is ABSORBED by surfaces and is then
RERADIATED from Earth to outer space in the form of longer, infra-red (heat)
wavelengths. Some energy coming in from the sun gets REFLECTED by clouds,
particles (ash, for example), or ice caps to outer space and is not absorbed by Earth. All
together, energy comes in and energy goes out. The result is an “Energy Budget” for
Earth, where incoming energy is positive and outgoing energy is negative.
http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif
QuickTime™ and a
decompressor
are needed to see this picture.
Seasons can be understood in terms of Earth’s Energy Budget. In summer months
incoming energy is greater than out-going energy. This trend in reversed in the winter
months.
Procedure
Visit each station and interpret maps that show Earth’s “NET ENERGY FLUX”
throughout the year. Energy flux is a measure of energy over area (Watts / meter^2). A
positive flux would indicate that there is more incoming energy. A negative flux
indicates that Earth is radiating more energy than it is receiving.
Computer Station: Animation of Net Energy Flux
Directions: Hit play or refresh to observe Earth’s net energy flux through out the
year. Look for basic patterns and trends. Answer the following questions. Replay as
needed.
1. a. What colors on the map correlate with high positive radiation? What does
this mean in terms of solar radiation?
b. What colors on the map correlate with low amounts of radiation? What does
this mean in terms of solar radiation?
2. a. What colors are the northern mid-latitudes (Ramsey ~41 N) during the winter
months (Jan – February)?
b. What colors are in the mid and polar latitudes in the southern hemisphere
in months (Jan. – Feb.)?
3. Use data from this animation to explain why the tropics (23.5 N – 23.5 S) don’t
experience seasons. (SENTENCES)
4. In broad terms, how does solar flux change through out the year? Describe
the pattern and relate it to seasons.
DECEMBER
Direction: Look at the TOP map (All-Sky Net Flux) in December. This image shows
Earth’s energy balance with the influence of cloud cover.
1. Which part of Earth is getting the most solar radiation (flux in W/m^2)? Give
latitude range.
2. Which part of Earth is losing energy (Negative flux)? Give latitude range.
3. What’s going on at the equator in terms of energy?
Direction: Now look at the BOTTOM map (CLEAR-SKY NET). This map
removes the influence of clouds on Earth’s energy balance. The image combines
data from satellite images taken on clear days. Ignore the white spots.
4. Compare the two maps (top and bottom). Describe HOW CLOUDS
INFLUENCE EARTH’S ENERGY BUDGET. (Hint: Look at the intensity and
distribution of reds). Do clouds increase or decrease energy absorbed by Earth’s
surface?
March
Direction: Look at the TOP map (All-Sky Net Flux) in March. This image shows
Earth’s energy balance with the influence of cloud cover.
5. Which part of Earth is getting the most solar radiation (flux in W/m^2)? Give
latitude range.
6. Which parts of Earth are losing energy (Negative flux)? Give latitude range.
7. What’s going on at the equator in terms of energy?
Direction: Now look at the BOTTOM map (CLEAR-SKY NET). This map
removes the influence of clouds on Earth’s energy balance. The image combines
data from satellite images taken on clear days. Ignore the white spots.
8. Compare the two maps (top and bottom). Describe HOW CLOUDS
INFLUENCE EARTH’S ENERGY BUDGET. (Hint: Look at the intensity and
distribution of reds). Do clouds increase or decrease energy absorbed by Earth’s
surface?
June
Direction: Look at the TOP map (All-Sky Net Flux) in June. This image shows Earth’s
energy balance with the influence of cloud cover.
9. Which part of Earth is getting the most solar radiation (flux in W/m^2)? Give
latitude range.
10. Which parts of Earth are losing energy (Negative flux)? Give latitude range.
11. What’s going on at the equator in terms of energy?
Direction: Now look at the BOTTOM map (CLEAR-SKY NET). This map
removes the influence of clouds on Earth’s energy balance. The image combines
data from satellite images taken on clear days. Ignore the white spots.
12. Compare the two maps (top and bottom). Describe HOW CLOUDS
INFLUENCE EARTH’S ENERGY BUDGET. (Hint: Look at the intensity and
distribution of reds). Do clouds increase or decrease energy absorbed by Earth’s
surface?
Conclusion
Answer the objective question (1) and (2) in paragraph form. Be sure to support
statements with examples and data from this activity. Use key terms where
appropriate.