美國與以色列的科學家發現，雲朵的形成會受到空氣懸浮粒子的明暗度影響，這解開了雲朵在全球暖化過程中扮演的角色。其中，空氣污染增進了太陽能量的吸收，則是解開這個謎團的重要關鍵。
上述研究公佈在最新一期的《科學》期刊網路版上。科學家在研究報告中說明，為什麼由空氣污染懸浮微粒和煙組成的「氣膠」（aerosol），有時候會阻礙雲朵的形成，但有時卻又助長雲朵形成。美國太空總署（NASA）高達太空飛行中心的科學家雷米爾（Lorraine Remer）說：「若空氣懸浮粒子吸收越多太陽光，便越容易阻礙雲朵的形成；不過，若懸浮粒子顏色轉淡，吸收的能量變少，懸浮粒子反而成為雲朵形成的助力。」
The formation of clouds is affected by the lightness or darkness of air pollution particles, U.S. and Israeli scientists have determined, solving one puzzing question about the role of clouds in global warming. The capacity of air pollution to absorb energy from the Sun is the key to the puzzle.
In a breakthrough study published today in the online edition of the journal "Science," scientists explain why aerosols - tiny particles suspended in air pollution and smoke - sometimes stop clouds from forming and in other cases increase cloud cover.
"When the overall mixture of aerosol particles in pollution absorbs more sunlight, it is more effective at preventing clouds from forming. When pollutant aerosols are lighter in color and absorb less energy, they have the opposite effect and actually help clouds to form," said Lorraine Remer of NASA's Goddard Space Flight Center in Greenbelt.
