Bacterial weather

  • Bacterial weather
    25.05.2011 13:23


    Researchers have found something odd going on in clouds.

    For precipitation to form, there of course needs to be moisture in the atmosphere -  which we see as clouds - but also a tiny particle around which small droplets of water or ice crystals can coalesce to form raindrops or snowflakes that are heavy enough to fall from the cloud.

    These are called condensation nuclei and are usually specks of dust or soot, or tiny seeds borne aloft.

    New research conducted by Alexander Michaud of Montana State University and Brent Christner, a microbiologist at Louisiana State, has revealed that some of these nuclei are living bacteria.

    Michaud looked closely at the layers of large hailstones that fell over Montana in June 2010, finding a few bacteria throughout but the highest concentrations near the core of the hailstones, suggesting an important role in their formation. 

    It is possible that some of these bacteria are "hitchhiking" the water cycle. The plant pathogen Psuedomonas syringae, for example, is known to aid the formation of snow. It can help ice to form at temperatures above the normal freezing point of water.

    The surrounding ice damages plants as it hits them, allowing bacteria to enter as the plants' cells break apart.


    By: Stephen Davenport