I understand that the sun gives energy primarily in the form of sunlight, which contains various wavelengths of electromagnetic radiation. If the earth absorbs some of the energy, does the earth’s “total energy” accumulate?
In: Planetary Science
The ratio of light that something reflects vs absorbs is called its “albedo.” An albedo of 1 means it is 100% reflective, an albedo of 0 means it absorbs 100%. For visible light, lighter colored things have a higher albedo – that is what it means for something to be lighter colored.
The albedo of the Earth overall is about 0.3, which means it absorbs about 70% of sunlight and reflects about 30%.
However, that solar energy that is absorbed doesn’t stay here. It is re-emitted back into space. The energy that the Earth emits is *almost exactly* the same as the energy that it absorbs. When these two are even very very slightly out of balance, the temperature of the Earth changes. Which is why for example having a bit too much carbon dioxide in the atmosphere causes global warming, because it very slightly reduces the energy that escapes.
Latest Answers