These beautiful cold phenomena are as interesting as they are strange
1
/
14
Polar vortex
The polar vortex is a natural cold phenomenon that surrounds the Earth’s north and south poles. This huge expanse of low pressure and cold air is always present around the poles, but it gets bigger during colder winter months, according to the National Weather Service (NWS). When that happens, the polar vortex can send Arctic air along the jet stream to the United States, as well as parts of Europe and Asia. The bitter blast can reach places that aren’t used to such cold temps, so bundle up.
2
/
14
Thundersnow
You read that right. Everyone has heard thunder during a thunderstorm, but … thundersnow? Yes, in cold climates, thunderstorms can happen in winter, too, and they produce thunder and lightning just like they would in the spring or summer. The difference is that instead of rain, you get snow: thundersnow!
3
/
14
Frozen Niagara Falls
In extremely cold weather, whole sections of flowing water can actually freeze. Niagara Falls, on the border of the U.S. and Canada, is stunning to see any time of year, but when this cold phenomenon happens, it’s amazing. In winter the falls can look like they’ve frozen in action, but actually there’s water moving underneath the surface.
4
/
14
Nor’easter
The name of this cold phenomenon is more self-explanatory than others. This winter storm usually has winds that develop in the northeast of the U.S. and move along the East Coast. Even though nor’easters can happen anytime of the year, they’re more likely to occur from September to April.
5
/
14
Hoarfrost
This strangely beautiful effect is caused when moisture in the air turns into to ice crystals that lightly coat an object, usually a plant. Hoarfrost is similar to frost, but less common, and the air must be moist, not dry, according to AccuWeather. Both the air and the object have to be at or around freezing, and in extreme cases, hoarfrost can grow several inches long.
6
/
14
Frost quake
You’ve heard of earthquakes, but what about frost quakes? Frost quakes, also called ice quakes or cryoseisms, happen when moisture in soil or rock freezes and expands rapidly due to a sudden temperature drop. The pressure created can actually cause the earth to break or crack, producing loud popping and even banging noises, which can be heard above ground.
7
/
14
Bomb cyclone
Bombogenesis sounds like a made up word, but it’s actually very real. More widely known as a bomb cyclone, this cold phenomenon occurs when the pressure inside a storm drops a certain number of millibars (a meteorological measure of pressure), depending on latitude, in 24 hours, according to NOAA’s National Ocean Service. Bomb cyclones can occur when a cold air mass runs into a warm one, often over ocean waters, causing the storm to rapidly intensify.
8
/
14
Frozen methane bubbles
Beneath the surface of Canada’s Lake Abraham in Alberta, bubbles of methane gas freeze on the way to the surface. The appearance—like glittering jewels—can be stunningly beautiful, but don’t get too close. Methane is flammable.
According to Smithsonian Magazine, when dead organic matter like leaves and animals sink to the bottom of bodies of water, bacteria get to work. When these critters expel waste methane, the bubbles float up, appearing as white floating blobs when they come into contact with frozen water near the surface.
9
/
14
Freezing fog
If fog is what happens when a cloud touches the ground, then what’s freezing fog? You guessed it, freezing fog is fog that occurs when it’s freezing or below freezing, and that means moisture on roadways can freeze, too, according to AccuWeather. That’s a real hazard in cold-weather climates. You could be looking at icy spots on bridges and overpasses, and even black ice (another cold phenomenon we’ll talk about ahead). Be careful out there!
10
/
14
Frost flower
Contrary to the name, a frost flower isn’t exactly a flower. It’s a cold phenomenon formed in freezing weather as the water in plant stems begins to expand as it freezes. This can cause vertical splits to form. The water leaving these splits freezes on contact with the frigid air, producing the flower-like structure you see here. The length of the split determines if the frost flower will be a narrow or wide ribbon, according to the NWS.
11
/
14
Black ice
Contrary to its name, black ice isn’t actually black. It’s a sheet of thin, transparent ice found on pavement. It’s notoriously difficult to see when driving or even when walking on the street, as the ice appears the same dark color as the roads.
12
/
14
Graupel
Graupel sounds like something out of Grimms’ Fairy Tales, but it’s an actual winter-weather term meaning soft hail or pellets of snow. Merriam-Webster says the first mention of graupel comes from a 1889 weather report, and the name itself comes from the Germanic word graupe, which means “pearl barley.”
13
/
14
Firn
Firn is the German word for “of last year” and can also be called névé. According to Britannica, firn is partially compacted snow that’s the intermediate stage between snow and glacial ice. It’s typically found at the head of a glacier, and takes about a year to form (hence the name).
14
/
14
Snow squall
Squalls are typically associated with storms with blustery winds, but in 2018 the NWS gave this cold phenomenon its own name. Described as an intense, brief snow storm with strong winds and whiteout conditions, a snow squall can drop 2 inches of snow in 30 minutes.
Why trust us
At Reader’s Digest, we’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. We’ve gone the extra step and had Marcy Lovitch, a fact-checker with 20-plus years of experience researching for national publications including Marie Claire, Good Housekeeping, Family Circle, Glamour, Seventeen, Real Simple, Forbes and InStyle magazines, verify that all quotes are attributed correctly and have credible sourcing. Read more about our team, our contributors and our editorial policies.
Sources:
- National Weather Service: “What is the Polar Vortex?”
- Live Science: “What is thundersnow?”
- Niagara Falls USA: “Ice Can Form on the River Every Winter”
- Maine Dept. of Agriculture, Conservation & Forestry: “Cryoseisms (or frost quakes) in Maine”
- National Ocean Service: “What is bombogenesis?”
- AccuWeather: “What is freezing fog”
- Merriam-Webster: “Graupel”
- Britannica: “Firn”
- National Weather Service: “Snow Squall FAQ”
- Smithsonian Magazine: “Stunning Bubbles Frozen Under Lake Abraham”
- AccuWeather: “What is hoarfrost?”
