Section 2.2A series of tropical cyclone formation research projects determined that there are six environmental factors which influence TC formation (these are discussed below). In general, all six of these parameters are satisfied over the tropical oceans at any given time, especially during the summer months. Thus, there must be a change (increase or decrease) in one or more of these variables for the formation of a TC. Typically, low-level vorticity and vertical wind shear are the most variable parameters, and are closely monitored for changes that lead to a favorable environment for TC formation.
It has been observed that TCs do not form within about three degrees of the equator (Fig. 3.3 and 3.4). Apparently a certain critical value of earth's vorticity is required for the formation of TCs. However, the likelihood of formation does not necessarily increase with increasing Coriolis parameter (i.e., moving away from the equator). Coriolis force is necessary for formation of a TC, but it is not sufficient to produce TC formation by itself.
Chapter 3
