A bomb cyclone is a storm which intensifies very rapidly. Bomb cyclones form when air near Earth’s surface rises quickly in the atmosphere, triggering a sudden drop in barometric pressure — at least 24 millibars within 24 hours.
It is a mid-latitude cyclone that intensifies rapidly. It is a massive winter storm hammering the coast, bringing strong winds, flooding, ice and snow. It is a combination of rapidly declining pressure and extreme cold.
As the air rises, wind spirals in at the base of the storm. As long as the air continues to rise at the top of the storm faster than it can be replaced at the bottom, barometric pressure will continue to drop. As with a hurricane, lower air pressure yields a stronger storm.
Bomb cyclones are caused when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengthening weather system is a process called bombogenesis, which creates what is known as a bomb cyclone.