What Is a ‘Bomb Cyclone,’ or Bombogenesis?
Bomb cyclones have been referred to as “winter hurricanes.” ...
What makes a storm a “bomb” is how fast the atmospheric pressure falls; falling atmospheric pressure is a characteristic of all storms. By definition, the barometric pressure must drop by at least 24 millibars in 24 hours for a storm to be called a bomb cyclone; the formation of such a storm is called bombogenesis.
... the storm, notable for a steep drop in atmospheric pressure that prompted some forecasters to describe it as a “bomb cyclone,” was but one act in a prolonged run of misery that had already enveloped millions of people in a wintry torment of Arctic air and snow-blown streets.
What exactly is a “bomb cyclone”?
A bomb cyclone is a low-pressure system that intensifies very rapidly—you have to have a fall in pressure of at least 24 millibars in 24 hours to qualify as a “bomb cyclone,” or “bombogenesis,” event. When a storm has its pressure rapidly fall like that, it’s going to drive stronger winds, because winds try and blow to equalize differences in pressure. The atmosphere doesn’t like to have different pressures, so what will happen is the wind will flow from high pressure to low pressure to try and balance out the difference.
Between Wednesday and Thursday morning, the storm strengthened at an astonishing rate, surpassing the meteorological criteria to be considered a so-called “bomb cyclone.” A storm is classified as such if its pressure falls 24 millibars in 24 hours. This storm’s pressure tanked 53 millibars in 21 hours (and 59 millibars in 24 hours), which puts it into the upper echelon of the most explosive East Coast storms ever observed — and perhaps even at the top.