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Author: Fulcrum Institute Development Team

Challenge Solutions/Discussion

Challenge 1 Solution

Let’s consider what happens to the light from the sun in two different cases:

Case 1 – transparent plastic on the outside, black raincoat on the inside

The plastic coat is transparent to the wavelengths of the energy being radiated by the sun. The energy carried by the electromagnetic waves is absorbed by the black raincoat. The black raincoat in turn radiates energy – half in an outward direction and half inward toward the body. Much of the energy that the black raincoat radiates is at a longer wavelength – a wavelength that is absorbed by the plastic. The plastic now heats up and radiates energy both outward and inward toward the black raincoat. The net result is some part of the half of the energy that the black raincoat radiates outward is captured because of the presence of the plastic coat and heats the blanket of air between the two coats.

Here is a schematic drawing of what is going on:

Schematic drawing of a transparent plastic on the outside, black raincoat on the inside

Case 2 – black raincoat on the outside, transparent plastic on the inside

The black raincoat absorbs the energy being radiated by the sun. The black raincoat in turn radiates energy – half in an outward direction and half inward toward the body. The half that is radiated outward is lost for the purpose of warming the person.

Here is a schematic drawing of what is going on:

Schematic drawing of a black raincoat on the outside, transparent plastic on the inside

Challenge 2 Solution

The atmosphere is the earth’s transparent plastic coat!