In certain circumstances the central pressure inside a frontal depression can fall at a very rapid rate forcing violent winds from the system known as 'bombs'.
A 'weather bomb' is not a perfect meteorological term but is defined as an intense low pressure system with a central pressure that falls 24 millibars in a 24-hour period. A better description can be more directly linked to the meteorological phenomena known as rapid or explosive cyclogenesis. This is where dry air from the stratosphere flows into an area of low pressure. This causes air within the depression to rise very quickly and increases its rotation, which in turn deepens the pressure and creates a more vigorous storm.
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.
Last updated: 9 December 2014