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Albedo Loss

Albedo Loss: Rooftop Reflection Reversal

The loss of Albedo (reflection) has caused less sunlight to be reflected away from the Earth. Now more sunlight is being absorbed worldwide. This makes everything hotter. Can rooftop reflection increase a reversal in the loss of reflection know as the albedo effect? One young Scientist thinks that it can.

According to Ryan (an under aged writer) for the American Museum of Natural History (AMNH), citing the scientist Wei-Chyung Wang, Albedo is defined as incident radiation divided by reflected radiation. Wang calls this the feedback effect.

Green house gases have caused the polar ice and snow to melt away itself, rather than refract light away.

As this feedback effect diminishes, more albedo is lost, even more ice and snow melts away, into a cascading environmental catastrophic disaster.

NASA Video: Loss of the sea ice

According to Ryan’s young naturalist report to AMNH the EPA says that he temperature in urban areas is 2-6o C hotter than in non-urban areas.

Deflecting some of the daylight away by 0.08% in L.A. could reduce this temperature by 1.5o C, according to Ryans research for the AMNH.

Ryan points out with annotation that research has shown that a building with a white roof top deflects 22% of the suns ill effect.

Ryan continues to point out the US Environmental Protection Agency wants to see a switch to higher albedo producing rooftops as people re-roof their homes, after the old roof needs to be replaced.

The albedo of an object like snow absorbs 90% where a surface like a forest canopy that is dark is very low. That is on a scale set from 0% to 100% absorbency. This is according to Lawrence Livermore/Carnegie Institution study on weather agriculture has increase the albedo in some regions through the clear cutting of forests.

The Lawrence Livermore/Carnegie Institution study found that forest are 1.3% more efficient at cooling the entire Earth that the more light absorbent surfaces below them. This due to the process by which leaves convert, inhale and exhale gas from pours on the underside of leaves called stomata. This water producing process is called transpiration. It accounts for 10% of the Earths water according to the report.

So what about Ryans point that the EPA suggests we make a switch to albedo producing surfaces. Would solar panels remove the radiant heat and deflect? Or what effect would roves made of solar windows; that is roves made mostly of glass treated with light absorbing dye? What about the proportion of moisture produced if tax credit and carbon stock is issues for converting to ecoroves?

Ryans study applied to asphalt shingles painted with a highly reflective coating; silver corrugated tin; black asphalt shingles; tin painted with a highly reflective coating. Ryans study is valid. People are not yet ready to all convert to eco-rooftops.

However the among the list of roof types the study did need to include solar paneling. Adding an eco-roof that provides a statistical basis for large-scale urbanized eco roofing would be an interesting study for Ryan to as a follow-up to his first study. Building an ecoroof is much more time consuming. It also requires a heavier investment, just like solar panels or dyed solar absorbent glass.

Ryans study on the albedo increase from the various surfaces he did have proved that white shingles worked best at keeping the dog house cooler.

His research into rooftop reflection albedo reversal is being recognized nationally as a possible solution to ambient city heat.




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Posted in Solar Times by admin on October 8, 2008.

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