PrintExperiment 2: A Fluctuating Sun
The Solar Constant is not really constant over any length of time. For instance, it was only 70% as bright early in Earth’s history, and it undergoes much more rapid fluctuations (and much smaller) in association with the 11-year sunspot cycle. During a sunspot cycle, the solar constant may vary by as much as 0.3 W/m2. Let’s see what this would do to the temperature of the planet. The model has a small switch called the Solar Cycle Switch that we can use to turn on or off the effects of the solar cycle. Set the model up with the following parameters:
| Practice | Graded | |
|---|---|---|
| Albedo | 0.30 | 0.30 |
| CO2 Mult | 1.0 | 1.0 |
| Solar Mult | 1.0 | 1.0 |
| Initial T | +15 | +15 |
| Ocean depth | 100 for #5,6, (200 for #7) | 150 for #5,6, (50 for #7) |
Questions
5. Run the model and see what happens. How much does the planetary temperature change over the solar cycle (the difference between peak and trough — measure this after the third peak)?
Change in temperature in one cycle =
6. Notice that the temperature peaks after the Solar Input peaks. This time delay is called lag time. What is the lag time here in years?
Lag Time =
7. Predict how the model will change if you increase the ocean depth to the second specified depth (table above). How do you think the lag time and the magnitude of temperature will change relative to the first solar cycle model (#5,6)? In other words, make a prediction. It might help to think about what heats up faster — a pot with a little water in it, or the same pot with a lot of water in it?
- Lag time shorter, magnitude smaller
- Lag time shorter, magnitude greater
- Lag time longer, magnitude smaller
- Lag time longer, magnitude greater
Be sure to reset everything in the model before going to the next problem.