Saturday, July 31

Why Snow Storms Hit the Northern Hemisphere

It’s as if the world has been turned upside down, or at least its climate.

You can blame the increasingly familiar polar vortex, which has brought the flavor of the Arctic to places where winter often requires nothing more than a jacket.

Around the North Pole, the ultra-cold winter air generally stays bottled at an altitude of 15 to 30 miles.

Parts of the US are being hit by unprecedented snow. (Getty)

That’s the polar vortex, spinning like a top on top of the planet. But every now and then something hits the top, sending cold air escaping from its arctic home and heading south.

It has been happening more frequently and scientists are still not entirely sure why, but suggest that it is a mix of natural random weather and human-caused climate change.

This particular polar vortex breakout has been huge.

Meteorologists call it one of the biggest, nastiest, and longest-lasting they’ve seen, and they’ve been observing it since at least the 1950s.

The weather this week is part of a pattern dating back to January.

Chernihiv police help a car to move in deep snow.
Police in Chernihiv, Ukraine, help a car move in deep snow. The polar vortex is affecting countries throughout the Northern Hemisphere. (Chernihiv Police)

“It has been a major collapse,” said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center on Cape Cod in the United States.

“It really is the cause of all these crazy weather events in the northern hemisphere.”

“It has been unusual for a few weeks, very, very crazy. Totally upside down. “

Cold record in warmer places

Record freezing temperatures in the US states Texas and Oklahoma took millions off the power grid and froze them. A deadly tornado struck North Carolina.

Other parts of the south saw blizzards and reports of something that looked like a snow tornado but was not.

Snow fell hard not only in Chicago, but also in Greece and Turkey, where it is much less normal. A record cold also hit Europe this winter, earning it the name “Beast from the East.”

“We’ve had everything you can imagine this past week,” said Northern Illinois University meteorology professor Victor Gensini, noting that parts of the US have been 28 ° C colder than normal. .

“It has been a wild ride.”

How the polar vortex works. (CNN)

Tuesday was warmer in parts of Greenland, Alaska, Norway and Sweden than in Texas and Oklahoma. And somehow, people in South Florida have been complaining about record heat that is causing plants to bloom early.

In the eastern Greenland town of Tasiilaq, it’s about 10 degrees Celsius warmer than normal, which “is a bit of a bummer,” said Lars Rasmussen, curator of the museum at the local cultural center.

“The warm weather makes dog sledding and snowmobiling a bit tricky,” he said.

Several meteorologists directly blamed the rupture or disruption of the polar vortex.

These used to occur once every two years, but research shows they are now close to happening annually, if not more, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial company outside Boston.

The spinning top falls off

Snow covers the ancient hill of the Acropolis of Athens. This vortex is unprecedented, some say. (AP)

The polar vortex winters in its normal place until an atmospheric wave, the kind that brings weather patterns here and there, hits it.

Normally, such waves don’t do much to the strong vortex, but occasionally the wave has enough energy to push the top and that’s when the icy air is released, Gensini said.

Sometimes the cold air mass splits into chunks, an event that is usually related to major snow storms in the eastern US, like a few weeks ago. Other times, you just move to a new place, which often means bitter cold in some parts of Europe.

This time he did both, Cohen said.

There was a vortex split in early January and another in mid-January. Then, in late January, the displacement occurred, causing cold air to spill over Europe and much of the United States, Cohen said.

Winter storm leaves Texans without access to electricity

Both Cohen and Francis said this should be considered not one, but three disruptions of the polar vortex, although some scientists group it all together.

While both the vortex and the wave that hit it are natural, and polar vortex ruptures occur naturally, there is likely an element of climate change at play, but science is not sure to agree, Cohen said, Gensini and Francis.

Warming in the Arctic, with shrinking sea ice, is driving the atmospheric wave in two places, giving it more energy when it hits the polar vortex, making it more likely to disrupt the vortex, Cohen said.

“There is evidence that climate change may weaken the polar vortex, making the icy air from the Arctic more likely to leak into the 48 continental states (the contiguous United States),” said Marshall Shepherd, professor of meteorology. from the University of Georgia.

Zach Mayer builds a snowman as snow falls on the Capitol in Olympia, Washington. (Ted S Warren / AP)

The pattern has been observed for decades

There were strong polar vortex disruptions and cold outbreaks like this one in the 1980s, Cohen said.

“I think it’s historical and generational,” Cohen said.

“I don’t think it’s unprecedented. This arctic outbreak needs to be thought of in context. The world is much warmer than it used to be. “

It also feels colder because just before the outbreak, much of the United States was experiencing a milder-than-normal winter, with the ground not even frozen on Christmas Day in Chicago, Gensini said.

The globe as a whole is about the same temperature as the 1979-2000 average for this time of year, according to the University of Maine Climate Reanalyzer.

Pictures of the week: snow covers the northern hemisphere

That’s still warmer than the 20th-century average, and scientists don’t think this month has much of a chance of being colder than the 20th-century average for the world – something that hasn’t happened since the early 1980s.

One reason is that it will soon rewarm to normal when the polar vortex returns to its usual home, Cohen said.

As for people who think that this cold outbreak disproves global warming, scientists say that it definitely is not.

Even with climate change, “we will still have winter,” said North Carolina state climatologist Kathie Dello.

“What we are seeing here is that we are not prepared for almost all types of extreme weather. It’s pretty sad, “he said.

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