We meteorologists have some pretty sophisticated and expensive weather instruments. But there's at least one that's neither pricey nor fancy. It's the ruler, still the instrument of choice for measuring snow.

Now, you might think that measuring snow is the simplest weather observation there is. In reality, accurately measuring how much snow falls is, in some ways, a no-win exercise. That's because accumulating snow compacts under its own weight, generally leading to underestimates of the true snowfall. Plus, the wind can create drifts that inflate snowfall in some places while skimming snow from others.

For official purposes, the Weather Service requires observers to measure snowfall every six hours on a snowboard, basically a piece of white plywood. If the snow has drifted, you take several measurements and average them. At some observation sites, snow isn't even measured directly anymore - instead, snow that collects in a rain gauge is melted, and then a formula is used to estimate how much snow actually fell.