Answers to Optional
Assignment #3

Comments
1. You should keep latent heat energy transport in mind
whenever you see mention of water or water vapor. However latent
heat energy transport requires a phase change. There is no
mention of a phase change in Question #1.
2b. 50 C is halfway between freezing and boiling. 50
F isn't even close to half way.
3. An object with a smaller mass would normally warm
more. This tendency must be offset by a large specific
heat. A material with a large specific heat will more less than
an object with lower specific heat.
5. Hot soup or hot coffee evaporates. Evaporation
takes a lot of energy from the hot water and contributes to cooling the
water.
10. The upward pressure difference force depends on
the air surrounding the balloon.

Comments
14. The atmosphere is absorbing 4 units of energy, it must
emit 4 units to be in energy balance. The ground is absorbing 2
units of sunlight but emitting 4 units of IR radiation. It needs
2 units from the atmosphere to be in balance. At the top of the
picture 3 units of energy arrive from the sun. Only 1 unit is
shown leaving the atmosphere, 2 more units are needed from the
atmosphere. Thus the atmosphere emits 2 units upward and into
space and 2 units downward. That's a total of 4, just what the
atmosphere needs to be in energy balance.