The sun radiates
an enormous amount of energy.
How much of it does our planet
one two billionth part of the energy that the
sun sends out!
How is Energy Used on Our Planet?
of all, 34% is just reflected back by clouds and ice. This energy
goes out into space and is lost to us. The reflectivity of a
planet or moon is called its albedo.
42% of the energy
goes to warm the land and water. When the earth turns and the
warmed part is in darkness, some of this heat is radiated out
23% of the energy
makes water evaporate. Without evaporation, there would be no
rainfall, no redistribution of water.
1% of the energy
powers the wind and the ocean currents that affect our weather.
These currents cause seasonal variations in rainfall, such as
0.023 of the
energy is used for photosynthesis. Photosynthesis is the process
by which plants take in carbon dioxide and water and, with the
help of sunlight, turn it into glucose, water vapor and free
oxygen. This process provides food and oxygen for all the animals.
All life on earth is living on what the plants can do with .023%
of the sun's energy!
It is important
to remember that the energy available to life is limited. Life
forms struggle to get enough energy to keep on living and to
reproduce. A small, stony island may support grass and small
rabbits, but it will not support tigers and elephants because
the grass cannot capture enough energy to support large animals.
A few small predators, foxes, perhaps, will keep the rabbits
from becoming so numerous that they eat all the grass. If the
island is in a very cold climate the grass will grow more slowly,
and perhaps the herbivores will be lemmings, which are smaller
than rabbits. Some tiny islands support only plants, insects
and a few visiting birds.
Anne Viau. All rights reserved. This material may be used by
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