1. Earth’s Energy Balance Homework Questions

2. Albedo: the reflectivity of radiation (light) from a surface
Question 1:
Albedo: the reflectivity of radiation (light) from a surface
(e.g. snow has a high albedo, black earth has a low albedo)
Heat Sink: an object or substance that is effective at absorbing heat energy
(e.g. the oceans act as a massive heat sink of the sun’s radiation)
Heat Capacity: the ability of a material to absorb heat energy
(e.g. a material that doesn’t increase in temperature as much as another for the same amount of energy has a higher heat capacity)

3. Question 2:
Conduction and convection cannot occur in space because:
They both require a medium (i.e. a substance with particles) to transfer energy. Radiation does not require a medium and can transfer energy through space.

4. Question 3:
What is the range of wavelengths (in metres) for the part of the electromagnetic spectrum that: (a) we use to cook food, (b) that we use to take dental x-rays, and (c) that we use to see?
Microwaves - frequency: ~109 Hz, wavelength: ~10-2 m
X-rays – frequency: ~1017 Hz, wavelength: ~10-9 m
Visible light – frequency: ~1014 Hz, wavelength: ~10-6 m

5. Question 4:
Does warm water rise or fall in cold water? Explain why this happens.
Warm water rises due to convection – particles in warm water have greater energy, spread themselves farther apart, making the water less dense.

6. Question 5:
Explain why convection does not occur in solids.
The particles in solids are tightly held together by attractive forces, so they are not free to move significantly apart from each other. Convection requires that particles are able to move freely.

7. Question 6:
Explain why rocks and soil are poor heat sinks.
Rocks and soil are solids and so depend on conduction to transfer energy. Unlike some metals, they do not conduct heat very quickly.

8. Clean snow, dirty snow, evergreen forest, ocean water
Question 7:
List the following in order of highest to lowest albedo: dirty snow, clean snow, ocean water, an evergreen forest.
Clean snow, dirty snow, evergreen forest, ocean water
Source: Albedo-e hg.svg, from Wikipedia article “albedo”, accessed
September 2009)