A weird twist on snow

Published 6:15 am Tuesday, December 18, 2018

A lot of folks had their first taste of snow recently, and since snow is more welcome during the Christmas season, I decided to use it as this week’s topic. Trouble is I’ve written several articles about snow in the past, so I had to dig harder to find something fresh to write about. I did find something surprising, and would have to classify it as weird science. It involves something called heavy water, so prepare to go sub-atomic.

Heavy water is heavier than regular water because instead of having the normal two hydrogen atoms, it has a version of hydrogen atom that has an extra neutron in it, called deuterium (also called heavy hydrogen). So instead of H2O, heavy water is D2O, or deuterium oxide. It still has all the properties of regular water, but slightly heavier. Planet wide, around one water molecule out of 6000 is a heavy water molecule.

It turns out that snow contains around 40% less heavy water than normal water. And some research in Siberia suggests that plants watered with melted snow grow twice as fast as those watered with normal water. This would be a definite plus for plants growing in the far north that have a short growing season but lots of snow melt water to give them a boost. The science guys have determined that D2O slows down some chemical and biological processes, and so when heavy water molecules are reduced, plants grow faster.

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This brings us to the final question: why is there less heavy water in snow? To explain, let’s start with a humid air mass that’s traveling from a warm climate to a cold one. As the humid air cools, some of the water molecules will condense and fall out as rain along the way. The heavier D2O molecules have a higher tendency to condense than normal H2O, and so the humid air mass will gradually loose a higher percentage of heavy water molecules as rain. By the time conditions are right for it to snow rather than rain, the water in snow has a reduced amount of heavy water.

Heavy water is nothing new, as deuterium was discovered in 1932. It was important during World War II in the research and development of nuclear fission, something both Germany and the United States were racing to figure out for nuclear weapons use.

All this has got me wondering. Making snow cream is a family tradition that I still love because it tastes soooo good! Could it be that less heavy water means a better tasting snow? Just sayin.

Steve Roark is a retired area forester from Tazewell, Tennessee.