DaisyWorld - A Two Daisy Ecosystem
A. Run the Daisy World Model (use "Run Te" button) varying the solar luminosity fraction L from 0.60 to 1.30 and fill in the table below. (Note: don't hit the return key after changing the number L, just click on the run button.) Make sure the Dead Planet box is NOT checked. You will want to make several graphs of your results so put the values directly into an Excel spreadsheet (or other graphing program) to save yourself time. (You could copy the data from the output table for the model and paste directly into Excel. You will need to use the data text-to-column option in Excel to get the data into separate columns.)
| L, Solar Luminosity (fraction) | Avg Planet Temp (C) | Area of White Daisies (%) | Area of Black Daisies (%) | A, Planetary Albedo (fraction) |
| 0.60 |
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| 0.65 |
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| 0.70 |
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| 0.75 |
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| 0.80 |
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| 0.85 |
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| 0.90 |
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| 0.95 |
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| 1.00 |
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| 1.05 |
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| 1.10 |
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| 1.15 |
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| 1.20 |
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| 1.25 |
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| 1.30 |
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B. Now answer the following questions. Be sure to post all of your work in your STEM Explorations folder. Include your name and the name and level of this exploration!
- What is the smallest value of L that initiates daisy growth? (Fiddle with the model to get answer to nearest 0.01.)
- For smaller values of L, is the planet too hot or too cool for daisy growth? Which color daisies are first established?
- Is the local temperature in the black daisy fields warmer or cooler than that in the white daisy fields?
- What is the largest value of L before daisies stop growing? (Fiddle with the model to get answer to nearest 0.01.)
- For larger values of L is the planet too hot or too cool for daisy grow?
- As the solar luminosity increases which color of daisies are the last to stop growing?
C. Using Excel (or some other graphing program), make graphs of the following. Be sure to copy all of your graphs to your eFolio STEM Explorations folder in a file labeled with your name and the name and level of this exploration.
- Average Planet Temperature on the Y axis vs. Solar Luminosity L on the X- axis. Note the stable climate region.
- Area of Black and White daisies both on the Y axis vs. Solar Luminosity L on the X- axis.
- Area of Black and White daisies both on the Y axis vs. Average planet Temperature on the X- axis.
- Planetary Albedo on the Y axis vs. Solar Luminosity L on the X- axis.
D. Summarize your understanding by answering the following questions.
- Explain how Daisy World self-regulates its planetary temperature (homeostasis) in a two daisy ecosystem.
- Comment on how Daisy World applies to the faint young sun paradox. (Do a web search to find out about the faint young sun paradox).
- Comment on the idea that very small changes in climate forcing can result in large changes in the climate state of a planet. For example, some feel that our biggest concern regarding future climate change is not so much the gradual alterations to global temperature but the potential for large shifts in climate state brought about by some unforeseen mechanism.