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.