Monday, January 12, 2009

Bacteria Make It Rain?

Researchers at Stockholm University in Sweden have found tiny amounts of surfactant-like compounds in the atmosphere. They believe the compounds come from ground bacteria and foster rain production.

Surfactants are amphiphilic (part water soluble, part water insoluble) compounds that reduce surface tension and allow mixing of disparate substances. Surfactants are used in detergents and ski wax and, of immediate relevance to us, our lungs. Pulmonary surfactant reduces surface tension in our lungs allowing effective ventilation. Surfactant deficiency is a big problem in premature babies.

Surfactants in clouds would help break up water molecules and encourage rain. The Stockholm researchers hypothesize that bacteria may have been selected for the ability to make it rain. Even if bacterial surfactants facilitate rainfall, it's not clear that we can assume evolutionary causation. Regardless, it's an intriguing notion - that bacteria may have long ago accomplished a long sought human ability (from rain dances to Olympic cloud seeding), to control the weather. And it's a great example of the universality of processes. The same stuff that helps us breathe may have allowed bacteria to make it rain.

(image credit: treesforlife.org)