Cold weather gets a bad rap. In spite of all our disdain and however many times we falsely blame the cold weather for getting us sick, lower temperatures can coincide with some truly jaw-dropping natural phenomena. From roaring thundersnow to friendly sundogs, here are 10 weather events that only happen when the mercury drops.
Frosty air temperatures, even colder near the surface than at higher altitudes, produce sparkling ice crystals known as diamond dust. Shaped like needles, columns or plates, diamond dust appears like a fog but glistens when exposed to sunlight. Unlike snow, diamond dust falls from a cloudless sky and floats in the air. Though common in Antarctica and the Arctic, diamond dust occasionally falls from North American skies as well. The glittery snow may fall for days, but never sticks to the ground for long.
Thundersnow forms when updrafts — columns of quickly rising warm air — move toward cold air above. The clash of warm and cold results in electrical charge separation. Soon, the instability produces a lightning strike, followed by thunder. Usual thunder and lightning are made under similar conditions. The key difference is the air near the ground is warm enough to rise but cold enough to not turn the falling snow to rain.
While snowstorms may go on for days, snow squalls are heavy but brief storms accompanied by strong winds. Snow accumulation may be under an inch, but added winds give way to quick drops in visibility and whiteout conditions. Stay off the roads if possible. However, if caught in your car, turn on your headlights and hazard lights and keep plenty of distance between you and the next car.
Michael Chritton/Akron Beacon Journal/Tribune News Service
An ultra-rare occurrence, snow rollers require a delicate mix of conditions: snow sticky enough to adhere to itself but light enough to not cling to the surface, and wind strong enough to curl the snow but gentle enough to not blow it all apart. When all these conditions are met, the result is a huge cylinder made of snow, curled by the wind’s nudge and gravity’s pull.
Like snow rollers, a sundog requires just the right combination of circumstances to trick you into seeing three suns. Officially known as a parhelion, sundogs happen when light reflects off clouds of tiny hexagonal ice crystals high up in the atmosphere. Similar to a rainbow, light hits the ice and breaks it up into all its colors. The crystals fall and float and all you see is their reflection at eye level. The faint light from each crystal comes together to create a false sun.
© Marc Bruxelle/Dreamstime.com
Uncommon in temperatures above minus 22 degrees Fahrenheit, ice fog may produce a “sun halo” effect, like a sundog. Rather than being composed of dense water droplets like typical fog, ice fog is made up of densely crowded frozen crystals 12 to 20 micrometers in diameter.
Named for their resemblance to robed monks, these natural towers of snow can be inches or feet high. They are formed at high altitudes where ice skips the water phase and turns from a solid straight into a gas. The sun heats part of the ice quicker than others, resulting in a cluster of pillars pointed toward the sky. Until 2017, penitentes were thought to only exist on Earth. Then, astronomists found evidence of snow and ice penitentes on the dwarf planet Pluto.
Snownadoes or snow devils are rotating columns of wind that pick up snow. Unlike usual tornadoes, snownadoes do not require surface heat to develop. Just six snownadoes had ever been caught on camera as of 2016. In 2019, two more were captured; one by a rancher in New Mexico and another by a skier in Colorado, one of the states with the most snowfall.
Todd Maisel/New York Daily News/Tribune News Service
In 2019, a bomb cyclone ripped across the U.S. from Minnesota to Arizona. The winter storm was responsible for some of the year’s craziest weather photos. Bombogenesis refers to the instance when a midlatitude cyclone’s atmospheric pressure rapidly intensifies, dropping at least 24 millibars (a metric unit of pressure) in a day. The bombogenesis creates a bomb cyclone, an intense winter hurricane. The lower the pressure, the more powerful the storm.
Also known as cryoseisms, frost quakes are extremely localized; someone might not even feel the quake that just shook a neighbor awake. Caused by sudden deep-freezing of the ground, frost quakes are common during the first cold snap of the year. Snow helps to insulate the ground. However, when the surface is bare and temperatures drop from above freezing to below zero, conditions are ripe for a frost quake.
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