Distribution of Energy from the Sun
There are several things that can happen to the sun's energy as it reaches our planet. Some of the radiation is absorbed by the atmosphere, while some is reflected by the atmosphere and clouds. The Earth's surface reflects a small percentage of the sun's energy, but the vast majority is absorbed by the surface of the Earth.
The pie chart below shows the break down of the distribution of energy from the sun. You'll notice that more energy is absorbed by planet Earth than is reflected. Fifty one percent of the sun's energy is absorbed by the surface of the planet and 19% by the atmosphere and clouds (70% total absorbed). Atmospheric reflection accounts for 6% of the sun's energy, while 20% is reflected by clouds and 4% by the Earth's surface (30% total reflected). This means that 70% of the sun's energy is received by Earth and 30% of the sun's energy is lost back to space.
Of the 51% absorbed by the Earth's surface, a crucial 0.08% of that energy is absorbed by plants and used for photosynthesis. Why is this important? As you learned in the first semester, plants are at the base of almost all food chains and food webs. Without this small percentage of the sun's total energy, Earth's biosphere and living organisms would not be able to survive.
Last modified: Wednesday, 23 February 2011, 6:10 PM