"6" . _:vb6791697 "A cyclone whose central pressure drops at an average rate of at least one millibar per hour for at least 24 hours."@en . _:vb6791698 "1980 October, Frederick Sanders with John R. Gyakum, \u201CSynoptic-dynamic climatology of the 'bomb'\u201D, in Monthly Weather Review, volume 108, number 10, page 1596:"@en . . _:vb6791698 "A bomb for this study is defined as one in which the deepening rate is the geostrophic equivalent of at least 12 mb in 12 h at 45\u00BAN."@en . _:vb6791698 . _:vb6791697 .