What is a bomb cyclone?
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.
Here is how it works: Deep drops in barometric pressure occur when a region of warm air meets one of cold air. The air starts to move, and the rotation of the earth creates a cyclonic effect. The direction is counterclockwise in the Northern Hemisphere (when viewed from above), leading to winds that come out of the northeast — a Nor’easter.
Bomb cyclone refers to a phenomenon expected to occur as this weather event unfolds. The official term is explosive cyclogenesis, which is actually really common. The ‘bombing’ occurs when a low pressure system’s central pressure falls 24 millibars in 24 hours or less. This refers to a low pressure system, which is basically when the atmospheric pressure at sea level is lesser than the surrounding area. This, along with wind, forms a, you guessed it, cyclone. Millibars are a measurement to describe pressure. Earth’s standard surface pressure is about 1013 millibars. The further it drops, the more intense the cyclone gets. This bomb cyclone that is being experienced from Florida to Maine could produce winds similar to that of a hurricane, but that is only an assumption.