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What is a bomb cyclone? Extreme winter storm hits USA | World News

Although it may not sound like it, “bomb cyclone” is a legitimate scientific term, so named because the rapid formation of a storm is like a bomb exploding.

Millions of Americans have been warned that prepare for a bomb cyclone with blizzards, wind chill and temperatures down to -45.6C (-50.1F) – cold enough to get frostbite in less than five minutes.

A bomb cyclone or “time bomb” is a term used to describe a rapidly deepening area of ​​low pressure.

“More accurately, it should be called explosive cyclogenesis, which is when the central pressure of a low pressure system drops dramatically – by 24 millibars in 24 hours,” Sky News weather forecaster Kirsty McCabe said.

“These intense storms are bringing heavy rainfall and very strong winds. Very cold arctic air is moving into the US right now, and the cold weather is causing further complications.”

How is a bomb cyclone formed?

The sudden change in pressure is due to the interaction with the powerful jet stream, McCabe said.

“This is a fast-moving band of air high in the atmosphere that directs our low-pressure systems at the surface.”

“The contrast between cold, arctic air to the north and warm, tropical air to the south strengthened the jet stream, which in turn deepened the low pressure area.”

Lows overnight Friday night into Saturday morning
The painting:
Lows overnight Friday night into Saturday morning (temperatures in Celsius)

Why is it called a bomb cyclone?

Meteorologists compared the sudden drop in pressure to a bomb exploding, using words such as “explosive cyclogenesis” and “bombogenesis” to describe the process of storm formation.

The term specifically refers to the speed at which a storm forms, said Daniel Swain, a climate scientist at the University of California.

“It doesn’t necessarily refer to the absolute strength of the storm system,” he said.

Is the UK getting bomb cyclones?

Great Britain has experienced weather bombs, most famously the Great Storm of 1987.

A person wrapped in a blanket walks down a sidewalk as snow begins to fall in St. Louis PIC:AP
The painting:
It ends as snow begins to fall in St. Louis, Missouri. Image: AP

How is a bomb cyclone different from a hurricane?

“All bomb cyclones are not hurricanes,” Mr Swain said. “But sometimes, they can take on characteristics that make them look an awful lot like hurricanes, with very strong winds, heavy rainfall and well-defined features like eyes in the middle.”

Hurricanes tend to form in tropical areas and are driven by warm seas. For this reason, they are most common in the US in the summer or early fall, when the seawater is warmest.

In contrast, bomb cyclones do not need the mellow ocean water to form.

They can occur over land and sea and are most common between late fall and early spring, when warm tropical air meets cold arctic air.

“They have to happen at a time of year when there is a possibility of warm air and cold air at the same time,” Mr Swain said. It is the difference in temperature that promotes the pressure drop.

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The US will see its coldest Christmas in more than 40 years

Are bomb cyclones dangerous?

It depends. Sometimes bomb cyclones behave like conventional winter storms.

But sometimes they cause severe flooding, blizzards and wind speeds comparable to a Category 1 hurricane.

“Fundamentally, the impacts of a bomb cyclone are not necessarily different from other strong storm systems, except that rapid strengthening is usually a sign of a very powerful storm system,” Mr Swain said.

A big part of the danger lies in the fact that bomb cyclones can surprise people, he added.

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