YORK, Pa. — As showers moved through South Central Pennsylvania this weekend, a type of winter precipitation known as graupel also mixed into some of these storms. Graupel oftentimes gets confused for as hail, though it forms in a different way.
To understand how graupel forms, you have to look at the atmosphere starting at the cloud! Snow forms in the cloud where temperatures are below freezing and eventually falls.
As the snow falls, it encounters a layer of air with supercooled water droplets. Theses are liquid water droplets that have a temperature below 32 degrees. Once that snowflake enters this layer, the water droplets freeze and stick to the snowflake. In meteorology, this is known as rime.
Eventually, the snowflake is covered by so many of these supercooled water droplets that they become tiny, white pellets. They look like hail, but are actually different. Graupel are typically soft and crushable, oftentimes compared to cotton candy!