Rain 3 Bacteria
Ambience – rain
In order for a cloud to make rain, the water in clouds must first freeze, and for many years, atmospheric scientists were mystified by why cloud water could freeze at relatively warm temperatures. I’m Jim Metzner and this is the Pulse of the Planet. Boris Vinatzer is an Associate Professor of Plant Pathology. He tells us that for cloud water to freeze, there has to be something in clouds a particle of some kind, that would help the water molecules to crystalize.
Vinatzer: Atmospheric scientists knew that there must be impurities in clouds that make water freeze at relatively high temperatures. Not being biologists, they studied inorganic matter. They did not find any inorganic matter that could make water freeze at temperatures higher than minus ten degrees Celsius. They were very surprised when they heard that organic matter could make water freeze at much higher temperatures.
One kind of organic matter that stimulates water to freeze is a bacteria called pseudomonas syringae,
Vinatzer: These bacteria have on their outside me membrane, a protein. And that protein has a structure that binds individual water molecules at exactly the same distance at which water molecules are in ice crystals.
So whenever the bacteria emits or as scientists say, expresses this protein, the water molecules line up and freeze at a higher temperature than they normally would, and we get rain. For a while, scientists thought they could seed clouds with pseudomonas syringae to make it rain. There’s one major problem though, and we’ll find out what that is in future programs.
Pulse of the Planet is made possible in part by Virginia Tech, inventing the future through a hands-on approach to education and research.