'Frost Flowers' And 5 Other Interesting Phenomena Our Meteorologists Watch For In Winter

So-called "f​rost flowers" spotted recently in Tennessee were a reminder of some of the interesting phenomena our meteorologists watch out for in the colder months of the year.

H​ere's a rundown of what exactly these icy "flowers" were, along with five other wintry features we keep our eyes peeled out for in social media.

1​. Frost Flowers

F​rost flowers are fairly rare to see, but conditions over the Thanksgiving 2024 holiday near Ridgetop, Tennessee, allowed Morning Brief newsletter reader Leslie R. Ratliff to pass along the great example below.

They develop where there is moist, unfrozen soil during below-freezing temperatures (32 degrees or lower).

Water pulled up from the soil into a plant's stem freezes, expands and splits the stem. As more water is drawn up through the stem split, more freezing occurs, eventually forming a fragile petal of the frost flower.

These amazing formations often melt or sublimate (transition from ice to water vapor) quickly after sunrise.

2. P​ancake Ice

Resembling frozen lily pads, pancake ice forms when there is some wave action on a body of water and temperatures are just below freezing.

Pancake ice can begin as a thin ice layer (known as grease ice) or slush on the water surface, which accumulates into quasi-circular disks. The "lily pad," or raised-edge appearance of pancake ice, can form when each disk bumps up against one another, or when slush splashes onto and then freezes on the slab's edge.

The floating disks of ice can be up to 10 feet in diameter and four inches thick.

3. S​now Rollers

This winter phenomenon occurs when strong winds pick up moist snow and blow it along the ground, eventually building a cylinder of snow that is often hollow in the middle. When the snow roller grows too large for the wind to propel it farther, it stops

Here are the optimal conditions for snow roller generation, according to the National Weather Service:

• Existing icy or crusty snow cover, so additional snow will not stick to it.
• Additional wet, loose snow on top of the icy, crusty snow cover.
• Wind strong enough to scoop out balls of snow and propel snow roller forward.
• At least some slope to the ground.

4. H​oarfrost

Frost is not an uncommon sight during the cold months of the year, but hoarfrost is in a league of its own.

With the extra moisture in the air, the interlocking crystal patterns of frost become more intricate and much larger, building up to a greater depth on tree branches, signs and fences, as seen below.

5. B​oiling Water Freezing In The Air

An experiment we see sometimes during frigid arctic air outbreaks is tossing boiling water into the air.

Once airborne, the boiling water changes state into steam/ice as it enters the cold, dry air mass, which is based on the Mpemba effect.

It works best when the air is very dry in subzero temperatures.

You can hit the play button below to see an example of this when temperatures were in the minus 30s in Fairbanks, Alaska, during early December 2016.

I​f you're going to try this at home, make sure you throw the boiling water downwind and away from yourself.

6. T​hundersnow

For many meteorologists and weather enthusiasts, hearing the crack of thunder during a snowstorm triggers excitement.

When thundersnow occurs, snowfall rates tend to be very heavy, many times reaching an inch or more per hour.

A pocket of unstable air aloft is needed to generate this weather phenomenon.

Typically, these pockets of instability develop as upward bumps on top of the flat layer of snow clouds already in place. This development occurs in response to strong lifting from an upper-level disturbance in the atmosphere.

If temperatures are between 14 degrees and -4 degrees Fahrenheit inside the upward bump where the elevated pocket of unstable air resides, snowflakes and small hailstones can form. As the snowflakes and hail collide, electrical charges will build up, making lightning and thunder possible.

M​ost often, the lightning flash associated with thundersnow illuminates the cloud cover with no distinct bolt visible. However, on rare occasions we see cloud-to-ground strikes like this one from Idaho in March 2024.

Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.