I keep seeing more and more of these articles espousing the concept that bacteria serve as templates to cause a significant amount of Earth's precipitation (rain and snow). The conventional thought process is that high-surface area inorganic materials (i.e. soot and dust) make their way up into the clouds to act as nucleation sites for precipitation. I recently read a watered-down article in Discover (April 2012, "The Clouds are Alive", Douglas Fox), however, it appears that a number of articles have appeared in Nature and Science over the last several years promoting this idea that rain is controlled primarily through a biological process. http://www.nature.com/news/2008/080228/full/news.2008.632.html http://www.nytimes.com/2010/05/25/science/25snow.html
Rain is just the result of evaporated water getting cooled enough to revert back to its liquid form... Gravity takes care of the rest...
By raising the ambiant temperature, reverting water from it's gaseous form to its liquid one. This is basic chemistry stuff that we did in highschool.
anything else that produces an aresol can increase clould drop count also, which will cause percipitation as well. plankton was a big one. other then that i imagine biology plays a small small role.
But neither plankton or volcanic dust "produce" or manufacture or create rain. The water is already there. All that they do is produce heat which in turn make water vapor (gas) return to liquid (rain).
The water vapor is already there that's correct. But (ignoring pressure), In order for vapor to tranisiton to liquid or ice, it needs a surface of which to do it on. aersols, dust, ash, and ect. act as a nucli for water to condense on. without a surface to condense on water vapor can be heated to ctritical tempature or cooled below freezing and it will not condense into snow or rain. these particles i beleive have to be cooler then the vapor to allow the water to transfer the energy/heat to the particle when it condenses. So this is correct and aparently after googleing fungi spores and bacteria have been found amoung these nucleating particles in ice crystals which suggest they use it as a form of transporation much like pollen in wind.
Sure, but surface effects can impact condensation. From the article, it sounds like that's the role proposed by the bacteria:The same bacteria that cause frost damage on plants can help clouds to produce rain and snow. Studies on freshly fallen snow suggest that bio-precipitation might be much more common than was suspected. Before a cloud can produce rain or snow, rain drops or ice particles must form. This requires the presence of aerosols: tiny particles that serve as the nuclei for condensation. Most such particles are of mineral origin, but airborne microbes bacteria, fungi or tiny algae can do the job just as well. Unlike mineral aerosols, living organisms can catalyse ice formation even at temperatures close to 0 ºC.
I get what you ae saying but the thread titles suggest that rain is CREATED by the biological particle that end up in the air. This is false. First, rain or water isn't created by those particle, it is already there. Second, the ratio of inorganic particles vastly outnumber those few biological particles that offer enough of a surface for water to cling to during its transition from gaseous vapor to liquid.
In layman terms, rain is caused when evaporated water in the atmosphere clings to small particles and when the atmosphere can't hold any more it falls as rain. Bacteria has been found in quite high concentrations in the atmosphere and so may act as part of the small particles.
