Ask Ellen: How is ‘soft hail’ made?

Ask Ellen

GRAND RAPIDS, Mich. (WOOD) — Thursday’s weather hit quickly with a hard drop into cold temperatures and a return to snow.

Some viewers, like Lexi, noticed it wasn’t just snow that was falling across West Michigan, but also small spongy balls of frozen precipitation. These cold springy pellets are known to meteorologists as graupel.

Courtesty: Brenda VandenBerg 

This Ask Ellen comes from Lexi, who wondered how hail like this is made.

It’s an excellent question. Graupel is sometimes referred to as “soft hail,” but it forms completely differently from the big, hard, hail stones we saw Tuesday.

Instead of getting many coatings of ice in a storm cloud, like real hail, graupel gets one flash-freeze coating of ice. This is what gives it a spongy feel.

WHAT ARE THE DIFFERENT PRECIPITATION TYPES?

The first step to identifying graupel is to know what you are looking for. Graupel is the only type of precipitation that resembles Dippin’ Dots ice cream.

HOW ARE DIFFERENT TYPES OF PRECIPITATION MADE?

RAIN: Rain starts as cloud droplets when the environment is above freezing. Eventually, enough tiny cloud droplets form together that they fall from the cloud as liquid water.

SNOW: Snow is made when the atmosphere is several degrees below freezing. Water vapor will suddenly spindle out into a delicate flake, dendrite, column, star or needle. It will stay in snow form as long as its entire trip to the ground stays cold.

SLEET: Sleet happens when either a snowflake falling from a cloud melts as it falls to the ground, then refreezes before it lands. This turns it into an ice shard. The same thing can happen if a raindrop falls from a cloud and freezes on its way down to the ground.

HAIL: Hail forms when there are clouds will strong updrafts. Hail begins as a tiny ice crystal. The strong updraft carries it into an area in the cloud where a glaze of hard ice flash-freezes around it. This process happens over and over again until the hail stone gets so big that it falls from the cloud. The stronger the updraft, the bigger the hail.

GRAUPEL: This forms when a single snowflake encounters a layer of super-cooled water droplets. The water droplets flash-freeze around the snowflake, giving it a spongy, springy, soft feel. It then falls to the ground.

You can submit your weathe rquestions to Ask Allen by emailing a video to the7on8@woodtv.com, or tag Ellen on Facebook or Twitter.

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