Would reflecting the sunlight heat up the upper atmosphere?

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Offline D

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You know how in New York a lot of people started to pain the roofs white, so i was wondering let say the entire state of NY paints the roofs white, would reflecting all that light effect the the upper atmosphere in any way? Or since the upper atmosphere less dense the light just going to pass through it with out having any effect on it?
« Last Edit: 26/08/2015 19:55:00 by D »


Offline Pecos_Bill

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It depends upon how much of what is in the upper atmosphere.

Here are some atmospheric gases which absorb energy in the visible and infra-red spectra : h2o, o2, o3,co2,n2o, ch4,co, and no2.

If you dump enough co2 and ch4 into the atmosphere the atmosphere will heat up, the sea level will rise and you will be able to go scuba diving in buckingham palace and water ski in piccadilly.

Whatever color they have painted the roofs in new york.


Offline evan_au

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About 75% of the Sun's radiation makes it from low-Earth orbit down to ground level. A greater fraction of the infra-red light is blocked than is visible light.

The idea of painting the roofs white is to reflect the sunlight as visible light, rather than allowing the sunlight to heat up dark surfaces, which then re-radiate the energy in infra-red light, which is trapped more effectively by the greenhouse gasses.

So painting the roof white means that less sunlight energy will be trapped by the atmosphere. In theory, it would work: If all the roofs in New York City were painted white, and all the roads were resurfaced in concrete, that might make a small difference to the summer temperatures in New York City. It might change this microclimate by a measurable amount.

However, in practice, there are a lot of trees in New York State, and deserts or oceans in other places, so if you extended the same change globally, it will not change the climate of New York State (or the world) by a measurable amount.