global dimming
omg just watched the documentary on channel newsasia.
global dimming is the phenomenon of less solar energy reaching earth. it was discovered first in studies of light intensity over germany and israel. subsequently, scientists also noticed that evaporation rates decreased over the past decades. these observations did not seem to fit with the fact that earth was facing global warming.
however, contrary to popular belief, temperature is not a major factor affecting rate of evaporation. wind, humidity and more importantly sunlight affect rate of vaporation. it is the energy of the photons hitting the water surface that cause water to evaporate. so, if the rate of evaporation is decreasing, the light intensity must be decreasing as well.
air pollution is the cause of global dimming. this was derived from observations in the maldives. the northern islands of the maldives received dirty air from india, while the southern islands received clean air from the antarctica. scientists noticed that temperatures in the northern islands were cooler than those in the southern. this was because there were more particles of soot and sulphur dioxide present in the northern atmosphere. these particles block the sunlight, but more importantly they cause clouds to become like giant mirrors.
clouds form when water molecules condense around naturally occuring particles. when sufficient water has condensed around the particles, then rain forms. in polluted air, the larger number of particles mean that instead of having few large droplets, there are many small droplets of water. and these many small droplets reflect much more light than the few large droplets, resulting in dimming.
global dimming could have possibly caused famine. but worst still, it affects monsoon systems. it has caused the sahel region to experience drought in the 70s and 80s. during the equinoxes, sunlight hits directly on the equator, forming the tropical rainbelt at the equator. during the solstices, sunlight hits directly on the tropics, shifting the tropical rainbelt either north or south of the equator. however, sahel received no rain during the summer solstice. this indicated that polluted air was preventing the solar energy from reaching the seas.
seemingly, the solution is to reduce pollution. however, scientists have discovered that global dimming is helping to reduce the effects of global warming. if there was no global dimming, we could be facing even more problems. climatologists noticed during the three days after september 11, when flights were grounded, that temperature ranges increased by over 1 degree. and that was a lot for just three days. this was because with no aeroplanes in the air, there were no contrails as well. and this implied that contrails contributed significantly to global dimming.
if removing a small amount of contributor to global dimming could result in such great temperature increase, the implication is that if pollution was removed competely, it could drive global temperatures up like crazay!
currently, pollution is being solved, but nothing is being done to curb greenhouse gases emissions. thats mean we are driving our global temperatures up at a rate double than expected. and if this should happen, the consequences are terrible. when the greenland ice cap melts, sea levels could rise by a few metres. rainforests could also burn and release huge amounts of carbon dioxide. huge underwater methane deposits could be released into the atmosphere.
scientists predict that in one century, temperatures could rise by 10 degrees. is that crazay or crazay? burning of coal, oil and gas causes both global warming and global dimming. seems that we must find alternative energies as soon as possible.
well, if we clean up pollution without doing anything about greenhouse gases emissions, then we could really destroy earth. so why don't we just continue polluting the air to let global dimming counter global warming?
global dimming is the phenomenon of less solar energy reaching earth. it was discovered first in studies of light intensity over germany and israel. subsequently, scientists also noticed that evaporation rates decreased over the past decades. these observations did not seem to fit with the fact that earth was facing global warming.
however, contrary to popular belief, temperature is not a major factor affecting rate of evaporation. wind, humidity and more importantly sunlight affect rate of vaporation. it is the energy of the photons hitting the water surface that cause water to evaporate. so, if the rate of evaporation is decreasing, the light intensity must be decreasing as well.
air pollution is the cause of global dimming. this was derived from observations in the maldives. the northern islands of the maldives received dirty air from india, while the southern islands received clean air from the antarctica. scientists noticed that temperatures in the northern islands were cooler than those in the southern. this was because there were more particles of soot and sulphur dioxide present in the northern atmosphere. these particles block the sunlight, but more importantly they cause clouds to become like giant mirrors.
clouds form when water molecules condense around naturally occuring particles. when sufficient water has condensed around the particles, then rain forms. in polluted air, the larger number of particles mean that instead of having few large droplets, there are many small droplets of water. and these many small droplets reflect much more light than the few large droplets, resulting in dimming.
global dimming could have possibly caused famine. but worst still, it affects monsoon systems. it has caused the sahel region to experience drought in the 70s and 80s. during the equinoxes, sunlight hits directly on the equator, forming the tropical rainbelt at the equator. during the solstices, sunlight hits directly on the tropics, shifting the tropical rainbelt either north or south of the equator. however, sahel received no rain during the summer solstice. this indicated that polluted air was preventing the solar energy from reaching the seas.
seemingly, the solution is to reduce pollution. however, scientists have discovered that global dimming is helping to reduce the effects of global warming. if there was no global dimming, we could be facing even more problems. climatologists noticed during the three days after september 11, when flights were grounded, that temperature ranges increased by over 1 degree. and that was a lot for just three days. this was because with no aeroplanes in the air, there were no contrails as well. and this implied that contrails contributed significantly to global dimming.
if removing a small amount of contributor to global dimming could result in such great temperature increase, the implication is that if pollution was removed competely, it could drive global temperatures up like crazay!
currently, pollution is being solved, but nothing is being done to curb greenhouse gases emissions. thats mean we are driving our global temperatures up at a rate double than expected. and if this should happen, the consequences are terrible. when the greenland ice cap melts, sea levels could rise by a few metres. rainforests could also burn and release huge amounts of carbon dioxide. huge underwater methane deposits could be released into the atmosphere.
scientists predict that in one century, temperatures could rise by 10 degrees. is that crazay or crazay? burning of coal, oil and gas causes both global warming and global dimming. seems that we must find alternative energies as soon as possible.
well, if we clean up pollution without doing anything about greenhouse gases emissions, then we could really destroy earth. so why don't we just continue polluting the air to let global dimming counter global warming?
posted by ivan at 8:37 PM
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