In October 2012, Hurricane Sandy demonstrated the destructive power of extratropical cyclones – a well-studied storm type that undergoes a known physical and thermal transition. These systems begin as warm-core tropical cyclones that derive energy from the ocean. Over land, the storms transition to cold-core extratropical cyclones that derive energy from clashes between different air masses. Of the study's 45 inland storms that maintained or increased strength, 17 belonged to this category.