The following was originally published in the November 2012 issue of Nature Notes, Heartland Outdoor School’s newsletter:

Antarctica is the world’s largest desert. While most people think of deserts as hot and sandy, they are actually defined as places with a very small amount of precipitation a year. So if there is not much snow fall in Antarctica, why is it covered in ice and snow? The answer is simple: Antarctic snow does not melt very often. In fact, scientists actually study ice in Antarctica to find out what the weather was like thousands of years ago. How can ice tell us these things? When snow piles up, a lot of air is left between the snowflakes. As the snow compacts after a lot of accumulation, it traps all that air in the ice that scientists can then study. Ice and snow can also trap dirt, salt, pollen, and other particles that tell a scientist about what happened in the past. In fact, snow is often formed around a speck of dust. When moisture freezes around the speck, each snowflake formed is completely unique. We know this because of a scientist named Wilson Bentley, who used a microscope to take over five thousand pictures of snowflakes. He said this about snowflakes: “Under the microscope, I found that snowflakes were miracles of beauty; and it seemed a shame that this beauty should not be seen and appreciated by others. Every crystal was a masterpiece of design and no one design was ever repeated. When a snowflake melted, that design was forever lost. Just that much beauty was gone, without leaving any record behind.”