Today’s Factismal: Twenty-eight inches of snow fell in Middletown, Connecticut in 1897 in one day.
Snow is a fascinating form of precipitation. The atmosphere must be within a very narrow range of conditions for snow to fall; too warm, and you get rain (or sleet). Too cold, and you don’t get anything at all. If there is too much super-cooled water, you get graupel. If the snow hits a patch of warm air on the way down, it turns into ice pellets unless the air is close to the ground and you get freezing rain. And if the air is too dry, then you get nothing at all.
But snow is also fascinating because it is much less precipitation than it sounds like. On average, about a foot of freshly-fallen snow will melt into less than an inch of water! Despite that, snow is an important part of the hydrological cycle; many parts of the world derive a large part of their water throughout the year from snow that fell in the winter. As a result, knowing how much snow fell is vitally important to farmers, meteorologists, and climatologists.
The problem with measuring snow is that there aren’t any good ways to do it automatically. Because rain is a liquid, it is easy to let it pour into a cup and gauge the amount. However, snow is a solid which means that it blows around easily; any measuring gauge large enough to capture enough snow to provide a good measurement would also be big enough to allow the wind to blow the snow out of it. Though there are several types of automatic snow gauges being used, the most reliable method for measuring snow remains the snow board.
Just as you might think, a snow board is a board that you put on the ground that supports a stick with markings that tell you how deep the snow has gotten. Once every six hours, a meteorologist goes out and measures the amount of snow that has accumulated and then clears off the snow board for the next six hours of measurement. The problem with that is that it takes a lot of people to provide just a few measurements.
However, ever since 1997, a group of citizen scientists just like you have been helping the National Weather Service to measure snow and other weather phenomena. Through the Community Collaborative Rain, Hail and Snow Network (CoCoRahs for short), they have provided more than 27 million measurements of rain, snow, and hail to the National Weather Service. Their work has improved weather forecasting by giving more data to rate models and more information about local conditions. If you’d like to be part of this on-going effort, then please go to: