global warming is caused by the increased levels of carbon dioxide in the atmosphere. carbon dioxide absorbs infra red (heat). the more carbon dioxide i the atmosphere the hotter the atmosphere gets. heat comes from the sun (around half) but a significant proportion of the suns energy comes via visible light (around half) , around seven percent is ultra violet. wikipedia says this: The Earth's surface and the clouds absorb visible and invisible radiation from the sun and re-emit much of the energy as infrared back to the atmosphere. Certain substances in the atmosphere, chiefly cloud droplets and water vapor, but also carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, and chlorofluorocarbons,[20] absorb this infrared, and re-radiate it in all directions including back to Earth. Thus the greenhouse effect keeps the atmosphere and surface much warmer than if the infrared absorbers were absent from the atmosphere.[21] white paint reflects visible frequencies, that is something coated with white is more likely going to reflect the visible frquencies back into space rather than absorb the light and re-emit it in the form of heat. as heat is absorbed by carbon dioxide (a greenhouse gas) by painting your roof white you do 2 things. 1 you reflect a significant proportion of the visible frequencies of the sun back into space 2 you keep your house cooler and are less likely to run the air conditioning as much, which in turn means less coal is burnt to keep your house cool. do a experiment find a white car and a dark coloured car. touch the surface you should be able to touch the surface of the white car with your palm flat on it. now try the dark coloured car and chances are you will burn yourself. this is because more energy is being absorbed by the dark colour. this dark coloured material now emits heat which is absorbed in turn by carbon dioxide. the white / lighter coloured material reflects most energy away from it, and a fair proportion of that sails back into space without heating the atmosphere. find a shed roof and paint it white and see the difference before and after. paint stuff white and save the planet!!!!
why don't you read the post? it would help if you knew something about science as well if you are going to debate me
crazy horse i can't really explain it any simpler 1 around 50 percent of sunlight is visible light 2 around 50 percent of sunlight is heat 3 visible light is a frequency of light not absorbed by the atmosphere 4 some heat from the sun is absorbed by the atmosphere directly (greenhouse gasses which makes the atmosphere warmer). 5 heat from the sun also warms the surface of the planet and this heat is then radiated back into the atmosphere again being absorbed by greenhouse gasses. 6 visible light is poorly absorbed by the atmosphere, some of it gets reflected back by the atmosphere. 7 the visible light that doesn't get reflected back by the atmosphere is either reflected by the surface (eg a snow field) or absorbed by the surface (an asphalt carpark/ road). this absorbed light heats the dark surface. this heat is then radiated into the atmosphere and is absorbed by greenhouses gasses makiig the atmosphere warmer. 8 by painting your roof white and other surface you reflect aroud 50 percent of the visible enrgy from the sun, a significant amount of this is reflected back into space without heating the atmosphere. 9 by painting enough roofs you make buildings cooler and cool the atmosphere.
Okay, I'll play along. Lets say we did it. It would be an aesthetic nightmare, for starters. Then, mass blindness from glare on a sunny day. And after labor day, we'd have to change everything back again. Big waste of time if you ask me.
you mean an aesthetic nightmare like the villages in the greek islands that use white paint on most of the buildings? painting your roof white will make your house cooler, which means you use less power to cool the place. if you wanted to go hard core you could even ventilate your roof cavity. on a sunny day white paint would dazzle a few high flying birds , well probably not. the all white buildings on places like santorini aren't particularly dazzling, i know, i've been there. not everyone has money to pay for solar cells or anything else renewable, the average joe wanting to help the planet can paint his roof / walls white and make his house cool. some paints are insulative too which means your roof is even cooler which ultimately means your house is cooler too. if you are looking for a cheap, practical and low tech way of defeating global warming here it is.
I get your point. I really do. And, on a very small scale, it could work for a few folks who happen to live in extremely hot climates. (Maybe all pavement should be painted white too) BUT, if you look at the earth as a whole, most of it is NOT covered with buildings. Nor pavement. Tho it may seem that way if you are a city dweller. Another BUT... What about the pollution involved in making all that white paint? Foolishness. How about putting the HEAT on all the BIG polluters? How about not supporting them? That would go a lot farther than painting your roof.
you're right it would be easier to just deal with the situation rather than try a band aid. in the meantime the people who do understand the problem can do something that takes very little money. the carbon dioxide to make paint would pale into insignificance compared to the energy that white paint could reflect away from the planet. pavements would be difficult because of glare. even in the greek islands pavements aren't painted because of glare - plus they'd get dirty too quickly. the idea is to cool the planet quickly and cheaply, it could buy time and make air con more efficient , which means less coal burnt)
