In certain circumstances, the central pressure inside an area of low pressure can fall at a very rapid rate. These are known as ‘bombs’ and violent winds can develop around the system.
What is a weather bomb?
A 'weather bomb' is an unofficial term for a low pressure system whose central pressure falls 24 millibars in 24 hours in a process known as explosive cyclogenesis. Rapid acceleration of air caused by the jet stream high up in the atmosphere can remove air from the column, reducing its weight so causing pressure to fall at sea level. This in turn sucks in air which converges from surrounding regions resulting in faster and faster rotation of the circulation, in the same way that ice skaters spin faster by drawing their arms in. The resulting winds peak over a period of a few hours and can be strong enough to bring down trees and cause structural damage.
December 2014 weather bomb
The image below shows a weather bomb forming south of Greenland on 9 December 2014.
The weather charts below show the weather bomb forming on 8 and 9 December 2014.