How do tropical storms / cyclones form ?
To undergo tropical cyclogenesis, there are several favorable pre cursor environmental conditions that must be in place (Gray 1968,1979) : • Warm ocean waters (of at least 26.5C [80F]) throughout a sufficient depth (unknown how deep, but at least on the order of 50 m [150 ft]). Warm waters are necessary to fuel the heat engine of the tropical cyclone. • An atmosphere which cools fast enough with height such that it is potentially unstable to moist convection. It is the thunderstorm activity which allows the heat stored in the ocean waters to be liberated for the tropical cyclone development. • Relatively moist layers near the mid-troposphere (5 km [3 mi]). Dry mid levels are not conducive for allowing the continuing development of widespread thunderstorm activity. • A minimum distance of at least 500 km [300 mi] from the equator. For tropical cyclogenesis to occur, there is a requirement for non-negligible amounts of the Coriolis force to provide for near gradient wind balance to occur
