Cleaner air makes brighter skies
By Richard Black BBC News environment correspondent.
Human activities put tiny particles into the atmosphere. The amount of sunlight reaching the Earth's surface is increasing, two new studies in Science magazine suggest. Using different methods, they find that solar radiation at the surface has risen for at least the last decade.
Previous work had found the opposite trend, leading to a popular theory known as "global dimming". But the latest Swiss and US research indicates the dimming in the past has now been reversed, possibly because of reduced atmospheric pollution.