Photon Food Fight


The fact that more energy cycles between the surface of the earth and the atmosphere than the earth receives from the sun strikes me as one of the great marvels of nature.

NASA Budget

This is the earth’s energy budget according to NASA. You can see that while only about half of incident solar radiation at the top of the atmosphere is actually absorbed by the surface due to reflection and direct absorption by the atmosphere, nearly one and a half times incident solar energy is sent from the surface back up between radiation, evaporation, and convection.

This would be a prescription for deep freeze if the atmosphere did not send the equivalent of all the sun’ s energy back down again.

So how can it be that  more energy cycles between the surface and the atmosphere than the earth receives from the sun?

It boils down to water. Water just luuuves long wave radiation, commonly called infrared. It doesn’t care a fig for visible and ultraviolet light. Ice and water vapor are essentially the same, they absorb and start flinging (radiating) long wave photons every chance they get. It is just a material property of H2O.

To get things started, clouds, water vapor, and ice absorb long wave photons from the sun and start flinging them every which way, up, down, sideways. The ones flung down by the atmosphere and whatever few make it through from the sun hit the ocean and the land. Oceans cover seventy percent of the planet, and they love long wave photons  so much they absorb them all within a few microns of the surface and begin flinging them as well.

The photons the ocean surface flings down (say half) are themselves absorbed within microns. This is a losing game and all the photons are essentially contained within the first few millimeters and the net effect is that the ocean flings the photons back at the atmosphere.

The photon food fight is on. It continues day and night. Simultaneously, endlessly, a sun quantum and more.

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This entry was posted in Climate, Energy Budget, Photon Food Fight and tagged , . Bookmark the permalink.

2 Responses to Photon Food Fight

  1. Pingback: Everyone Loves Lists, Should We Worry or Not? | geosciencebigpicture

  2. Pingback: MODTRAN Up and Down VII | geosciencebigpicture

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