The role of oceanic plankton in cloud formation

Nobody knows what our skies looked like before fossil fuel burning began; today, about half the cloud droplets in Northern Hemisphere skies formed around particles of pollution. Cloudy skies help regulate our planet’s climate and yet the answers to many fundamental questions about cloud formation remain hazy.Satellites use chlorophyll’s green color to detect biological activity in the oceans. The lighter-green swirls are a massive December 2010 plankton bloom following ocean currents off Patagonia, at the southern tip of South America.NASA