SIO 217C: Climate
Spring 2014
Simple Greenhouse Model Discussion Questions
1. Why is the nighttime minimum temperature lower in a desert region than in a humid region
even when daytime maximum temperature is higher in the desert region?
2. Consider the rate of energy from the Sun passing through a 1 m2 area at the top of the
atmosphere when the Sun is directly overhead. How many 100 W light bulbs use energy at
the same rate?
3. Consider the rate of energy from the Sun passing through a 1 m2 area, averaged over all
latitudes and day and night. How many 100 W light bulbs use energy at the same rate?
4. The atmosphere absorbs about 23% of the incident solar radiation, on average. Consider the
rate of energy from the Sun absorbed by an atmospheric column with 1 m2 area, averaged
over all latitudes and day and night. How many 100 W light bulbs use energy at the same
rate?
5. Looking at ACC Fig. 3.1, consider the rate of thermal energy emitted plus solar energy
transmitted by the atmosphere downwards to a 1 m2 area on the surface of the earth, averaged
over all latitudes and day and night. How many 100 W light bulbs use energy at the same
rate?
6. Looking at ACC Fig. 3.1, consider the rate of energy emitted upwards by a 1 m2 area on the
surface of the earth, averaged over all latitudes and day and night. How many 100 W light
bulbs use energy at the same rate?
7. What impact, if any, does absorption of solar radiation by the atmosphere have on
equilibrium surface temperature (compared to no absorption of solar radiation by the
atmosphere)? Why?
8. In addition to radiation fluxes, the surface of the earth transfers energy to the atmosphere
through turbulent fluxes of sensible and latent heat. What impact, if any, does this have on
equilibrium surface temperature? Why?
9. What changes in the gaseous composition of the stratosphere would lead to a cooler
equilibrium stratospheric temperature? Why does the stratosphere cool in response to these
changes?
10. GPC Fig. 3.11 shows how radiative equilibrium temperature decreases from the surface
upward for a multilayer simple greenhouse model. In this model, what is the physical reason
for the decrease of temperature with height? Is it the same reason for why temperature
decreases with height in the troposphere?
Difficult Question
11. Imagine a planet similar to Earth but with an atmosphere filled with black carbon aerosol that
reflected some solar radiation and absorbed all the rest such that no solar radiation was
transmitted to the surface. Assume that the surface is a black body and the atmosphere may
be a graybody. How do surface temperature and atmospheric temperature on this planet
behave similarly or differently from the Earth?