DNA Explainer: What is Bomb cyclone, massive winter storm turning Christmas into chaos in US?

With temperatures dropping by as much as 50 degrees Fahrenheit in some areas and forecasters warning of an impending "bomb cyclone" that could make conditions even worse before Christmas, thousands of flights were cancelled and homeless shelters were overflowing on Thursday during one of the most treacherous holiday travel seasons the US has seen in decades.

On Thursday, meteorologist Ashton Robinson Cook from the weather service said that cold air was moving eastward over the central United States, and that roughly 135 million people will be under windchill warnings over the next several days. The wind chill in Des Moines, Iowa, will make it seem like negative 37 degrees, and frostbite may set in under five minutes.

What is a bomb cyclone?
Bomb cyclones are storms that get rapidly stronger. Typically, a pressure decrease of 24 mbars over 24 hours is required. However, this norm also considers the storm's latitude. It follows that the millibar may change based on the storm's point of origin. 

Why is it called a bomb cyclone?
Meteorologists used phrases like "explosive cyclogenesis" and "bombogenesis" to describe the storm's development, drawing parallels between the sudden decrease in pressure and the detonation of a bomb. The phrase "bomb cyclone" is really used in science, despite how it sounds. According to Daniel Swain, a climate scientist at the University of California, Los Angeles, the word "storm speed" is defined as the rate at which a storm develops in the American Meteorological Society's vocabulary. It's not a measure of the storm's intensity in and of itself, he said.

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How dangerous Bomb cyclones are? 
The behaviour of bomb cyclones is similar to that of standard winter storms. On rare occasions, though, they deliver heavy rains, snowstorms, and gusts that are on par with those of a Category 1 hurricane. According to Swain, the impacts of a bomb cyclone are, in principle, similar to those of other severe storm systems; the main difference is that a quick increase in intensity is often indicative of a very strong storm system. He said that bomb cyclones are riskier since they might catch people off guard, as reported by the media.