"Hidden" Optional Assignment Answers
1. About 30% of the sunlight reaching the earth is reflected back
into space, 20% is absorbed by gases in the atmosphere and the
remaining 50% makes it to the surface and gets absorbed. If 20%
of the incoming sunlight were reflected and 30% were absorbed by the
atmosphere, would you expect the earth and its atmosphere to
WARM
COOL
or remain at the SAME temperature?
Initially the earth and the atmosphere are absorbing 70% of the
incoming sunlight. After the change the earth and atmosphere are
absorbing 80% of the incident sunlight. The earth and atmosphere
will WARM. Because of
the warming the earth and atmosphere will begin to emit more energy
into space and reestablish energy balance between the amounts of
incoming and outgoing radiant energy.
2. Two units (arrows) of sunlight are shown
arriving at the top of the earth's atmosphere in the figure
below. One unit is absorbed by the atmosphere and one unit passes
through the atmosphere and is absorbed by the ground. The ground
emits 3 units (arrows) of IR light: one passes through the atmosphere
and the other two are absorbed.
How many units of IR light must the atmosphere emit? 3
How many of those units must go upward and into space? 1
How many units must go downward and be absorbed by the ground? 2
The atmosphere is absorbing 3 units of energy (Points a, b, and c) and
must therefore emit 3 units (arrows) to be in energy balance (shown in
blue in the figure above). The ground is emitting 3 units of
energy and only getting 1 unit from the sun (Point x). 2 of the 3
units of energy emitted by the atmosphere must point downward and be
absorbed by the ground (Points y and z). The remaining 1 unit of
energy emitted by the atmosphere goes upward and into space.
