Have you entered the treasury of snow?
One spring a friend trekked with a gaggle of students in the Cherokee National Forest up above the Ocoee River in eastern Tennessee. They were a good day and a half into a lovely stroll when the temperature plummeted and a freak spring snowstorm dropped more than a foot of snow on them. Since that part of Tennessee just doesn’t get very much snow, they were at first awed by the beauty of the freshly fallen snow. The beauty wore off quickly, however, when they realized that most of the students were simply not prepared for cold weather snow hiking, much less snow camping. They decided to cut their itinerary short and take the shortest route to shelter and safety. It wasn’t easy, but all did survive. But what made the freak snow in spring?
Meteorologists know that in order for rain or snow to fall, the air needs to be saturated with water vapor (i.e., 100 percent relative humidity), be cold, and have microscopic material for the moisture to condense on. Dust motes, smoke, and tiny particles of soot in the air work well, as do tiny ice crystals. Apparently such nucleation sites help orient water molecules so that they can easily form ice crystals. Scientists refer to the transformation from a supersaturated cold gas to ice crystals as a phase change. Once it has occurred, then the ice crystal can easily grow and start falling. As ice falls it may warm up and become a drop of rain. For years people have attempted to seed clouds with various types of nucleation material with varying degrees of success.
David Sands at Montana State University, Bozeman, Montana, has been working with Pseudomonas syringae, a type of bacterium commonly found almost everywhere on outdoor surfaces-especially plants. The bacterium makes a protein in its cell wall that provides thousands of nucleation sites. They orient water molecules effectively, causing freezing even when the temperature is well above normal freezing temperatures. Such bacteria-induced frost on plants causes extensive damage. The bacteria must get swept up into the air, because in 70 percent of snowflakes recently studied the microscopic bacterium and its magic protein turned out to be the nucleation site. This phenomenon, called bioprecipitation, is believed to be widespread, because everywhere Sands has looked, he has found the bacteria at the center of ice crystals. Could this magic icemaker bacteria be one of the treasuries of the snow that God was asking Job about?
Lord of the rain, snow, sleet, and hail, the science behind precipitation is so very complicated, yet You do it with apparent ease. We worship You as the giver of every good gift.