50 years ago, scientists suspected microbes flourished in clouds

Clouds may be ecosystems — Science News, November 14, 1970

Clouds in the sky may contain living microbial ecosystems…. [Research] determined that metabolic activity, in the form of CO₂ uptake into organic material, occurred in [airborne] dust over a 24-hour period, whereas it did not occur in sterilized control dust.

Update

The atmosphere is rich in microbial life. One census documented some 28,000 bacterial species in samples of water from clouds above a mountain in France, scientists reported in 2017. Research building over the last decade or so has supported the claim that some bacteria may indeed be metabolically active within their hazy abodes. One species of B­acillus, for example, eats sugar floating in the atmosphere to build a coating — perhaps to shield itself from ultraviolet radiation and low temperatures (SN: 2/7/15, p. 5). Some scientists suspect cloud bacteria contribute to Earth’s carbon and nitrogen cycles, and even influence weather (SN: 6/18/11, p. 12). The microbes can spur ice crystals to form, triggering rain and snow — and a ride back to Earth’s surface.