BOMB

A name applied to mid-latitude depressions which deepen violently. The term was coined by Sanders & Gyakum (US Monthly Weather Review), in a 1980 paper dealing with such events, and requires a pressure fall in the depression centre of 24 hPa (or mbar) or more in 24 hours at latitude 60degN for the name to be applied. At latitude 45degN, the required value is 19hPa, and at 55degN, 23hPa. (see Explosive cyclogenesis.)