Graupel, a “supercooled” type of precipitation

What is graupel? Look! Up in the sky! Is it snow? Hail? Sleet? No, you meteorological ignoramus, it's graupel! Of all the types of frozen precipitation that fall from the heavens, graupel is probably the most obscure. The Washington Post calls it "the wintry precipitation you've never heard of." Graupel from a 2013 storm in [...]