Snow Flakes Could Shed Light on Ozone Depletion in the Arctic
08.12.2009 - Atmosphere & Space, Water & Oceans, Ice & Snow, Other, Arctic
Ice chemists from Purdue University in Indiana are currently studying the variability of snowflake geometry to gain better insight into the dynamics of ground-level ozone depletion in the Arctic.
By studying the physical structure of the snow crystal, researchers hope to obtain a better understanding of the chemistry that occurs at the surface of a snowflake. Research conducted by growing snow crystals in a chamber shows that the shape of snow crystals can change depending on temperature and humidity, and can even go back and forth from one shape to another. A thin quasi-liquid layer of water that exists on the top and sides of all snow crystals - even those at temperatures well below freezing - causes the structure of the crystal to change under varying temperature and humidity.
In their research, scientists are growing snow crystals in order to study how the sharp transitions in the shape of snow crystals at different temperatures and humidity levels and understand the implications for the Arctic Ocean region. First conclusions in the study showed that it was the thin water layer on the top and sides of every snow crystal that caused the changes; the more water there is the more branches the snowflake will have.
The different shapes snow crystals take not only explains why two snowflakes are not identical but also has implications for ozone research in the Arctic Ocean region. Most people are likely familiar with ozone depletion at the Poles, which occurs in the stratosphere. However ozone levels also decrease significantly at ground level.
Ground-level ozone is important as it gives the atmosphere the ability to clean itself. Complex chemical reactions taking place at the thin layer of water on the surface of snow crystals cause the release of certain chemicals that reduce ozone at ground level. The speed of these reactions is partially determined by the crystal's surface area; the greater the surface area of the crystals, the greater the rate of reaction.
