Snowstorms are not unusual, but the intensity and record snowfall caused by these storms have prompted meteorologists to issue warnings, particularly in the United States, where a snowstorm referred to as “bomb cyclone” has occurred.
The origin of the “bomb cyclone” is cold, dry air that accumulates over the ice sheets in the Arctic. The movement of air currents in the stratosphere and higher up forces the cold air from the Arctic to move southward, reaching Canada and the United States.
When the dry, cold air descends into the warmer, moister region, the interaction between these two air masses creates the extreme weather phenomenon known as a “bomb cyclone,” a type of storm that rapidly intensifies, with atmospheric pressure dropping dramatically within 24 hours.
A man wrapped in a blanket while moving outside during snowfall in St. Louis, Missouri, USA. Photo: AP.
Storms can form when a low-pressure system meets a high-pressure system. Air moves from areas of high pressure to areas of low pressure, generating wind.
A bomb cyclone occurs when the pressure in the low-pressure system drops rapidly—by at least 24 millibars in 24 hours. This causes the pressure difference between the two air masses to increase swiftly, resulting in stronger winds.
John Moore, a meteorologist and spokesperson for the National Weather Service in the United States, noted that the Great Lakes region has the conditions conducive to producing a bomb cyclone. Here, the frigid Arctic air from the polar vortex meets very warm air from the east.
The atmospheric pressure drops to at least 962 millibars, while in other areas, it can reach up to 1047 millibars. “That is a very strong pressure difference,” he said.
Scientists are still debating various hypotheses. However, one theory that many scientists support is that the rapid warming of the Arctic has disrupted weather patterns.
Some scientists indicate that this warming phenomenon is causing disruptions in the polar vortex through changes in air currents.
Formation of the “bomb cyclone”. Graphic: BBC. (Translated by: Bao Chau).
According to Mr. Moore, as the area where the two air masses meet—known as the Arctic front—moves north and east, the conditions for the formation of snowstorms will continue to shift as well.
However, as the Arctic air spreads across most of the country, it will eventually warm up, reducing the pressure difference. The storms will then dissipate.
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The U.S. in “bone-chilling” cold, many casualties reported A sudden “horrific winter” has enveloped the United States, worsening since January 13 due to a wave of Arctic storms. Ice storm warnings in Oregon, blizzard warnings in the Northern Plains, and high wind warnings in New Mexico have been issued. A series of deaths related to the cold weather have been reported in California, Idaho, Illinois, and Wisconsin. Governor Jim Pillen of Nebraska declared a state of emergency due to “very dangerous” weather conditions. Over the week, snow accumulations reached up to 0.6 meters in some areas, with wind chills below 0 degrees. Approximately 1,700 miles of highways in Nebraska were closed, and police had to assist over 400 stranded drivers. The Arctic storms have also been the underlying cause of 86 collisions and 535 calls for assistance from drivers in Iowa since January 12. Many areas in Montana are struggling with terrifying temperatures of -34 degrees Celsius, while Northern Kansas is forecasted to reach similar lows, and South and North Dakota could drop to -46 degrees Celsius. In St. Louis, Missouri, the National Weather Service warned of a “rare and life-threatening” cold snap. |
