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 Dave Thurlow, Host |
No matter where you live, ice affects your life and a microscopic layer of water on top of ice affects your life more than you realize. Hi, I'm Dave Thurlow and this is The Weather Notebook.
Scientists have established that a very thin layer of liquid water sits atop any piece of ice, even far below 32 degrees Fahrenheit. This layer, called "premelt," is about 100 millionths of an inch in thickness.
Because the transition between water and ice is so important in our world, the environmental consequences of this film of premelt are large.
For example, the efficiency at which snow crystals scrub pollutants out of our atmosphere appears to depend strongly on their liquid surface layers, even at temperatures as low as zero degrees Fahrenheit. The premelt layer in high stratospheric ice clouds may affect the rate at which certain reactions produce ozone-destroying chemicals. And premelt layers may explain how electric charge transfers among ice particles causes thunderstorm lightning.
Liquid in premelt layers is drawn to the surface, where some of it freezes to form an ice lens, and water from below is then drawn upwards to continue the process.
So the next year when you slip on the ice, don't blame the ice, blame the premelt.
Today's show was written by David Appell. The Weather Notebook is underwritten by Subaru, with major support from the National Science Foundation.