Energy Balance

Not all solar energy that enters the top of the atmosphere makes it to Earth’s surface. Some of the energy is absorbed by the atmosphere, and some is reflected by the atmosphere and the clouds.

Scientist Asmeret Asefaw Berhe summarizes what happens to the solar energy that reaches Earth (clip from The Science of Climate Change).
A cartoon style diagram showing Earth, atmosphere, and the sun.
Energy that enters the top of the atmosphere (TOA) may be absorbed, reflected, or reach Earth’s surface. The proportions of each differ at different places on the planet.

Question 3

Complete the table to calculate the flux of energy in each location and category. All the information you need is already in the table. Select the numbers in the first row to show example calculations. Round to the nearest whole number.

A table comparing what happens to solar energy at the five locations from Question 2. Incoming solar energy at the top of the atmosphere (TOA) is either absorbed/reflected by the atmosphere or reaches Earth’s surface.
Location Incoming energy at TOA (W / m2)
The incoming energy at the surface divided by the percentage reaching the surface.
Incoming energy at surface (W / m2)
The incoming energy at the top of the atmosphere (TOA) multiplied by the percentage reaching the surface.
% Absorbed / reflected by the atmosphere
100% minus the percentage reaching the surface.
% Reaching the surface
100% minus the percentage absorbed/reflected by the atmosphere.
Arctic Tundra 198
103 W/m2 ÷ 0.52 = 198 W/m2
103
198 W/m2 × 0.52 = 103 W/m2
48
100% − 52% = 48%
52
100% − 48% = 52%
Gulf of Mexico
156 59
Temperate Forest
125
45
Tropical Rainforest 415
47
Tropical Savanna 401
44
Why might the percentage of energy reaching Earth’s surface vary among locations?
The energy entering Earth must equal the energy leaving Earth. Why do you think the energy is “balanced” in this way?