Follow the method we used in class to calculate Earth's radiating equilibrium
temperature.
Remember to use meters for distance (convert as needed).
1. Recall that the total output of the sun is approximately 3.865 x 1026 W. From this, and the distance to each planet listed on the table below, calculate the solar constant for Venus and Mars (fill in blanks in table).
2. Knowing the albedo of each planet (see table line 4), and using the Stefan-Boltzman Law,
calculate the equilibrium
radiating temperature for Venus and Mars (remember to convert Kelvin to Celsius -- again, fill in
the blanks in the table).
Stefan-Boltzman Law: I = s
. T4 (assume emissivity = 1.0)
where: I = intensity of emission, W/m2; s
= 5.67x10-8 W/m2/K4; T = temp in Kelvin
| Characteristic | Earth | Venus | Mars |
| Distance to sun (106 km) |
150 |
108 | 228 |
| Solar constant (W/m2) | 1367 |
|
|
| Radius of planet (km) | 6371 | 6049 | 3390 |
| Albedo (%) | 30 | 75 | 15 |
| Radiating temperature (oC) | -18 |
PART 2
3.
Now, study the data on surface temperature below. Note how much or
how little each planet's Greenhouse Effect adds to its surface temperature (fill
in the blanks on the table).
4. Considering the radiating temperatures along with the other data given on the table below, explain why the surface temperatures (or the Greenhouse Warmings) differ so much.
| Characteristic | Earth | Venus | Mars |
| Surface temperature (oC) | 15 | 427 | -53 |
| Greenhouse warming (oC) | +33 | ||
| Cloud cover (%) | 50 | 100 | 15 |
| Atmos. mass (Earth = 1) | 1 | 100 | 0.06 |
| CO2 (%) | 0.035 | >98 | >96 |
| H2O (%) | 0.0-4.0 | 0.0-0.3 | <0.001 |