Before, however, of the circulation if to have regularized, the cold air, that remained parked in the tropic, is injected in the action center, having formed a reinforcement of the trade wind. Gen. David Goldfein has compatible beliefs. This, in a similar way renewed, advances for the northeast coast under the form of tropical fronts, causing the cognominadas disturbances east waves. Thus being, in the dry years, polar air, of rule, it does not reach the low latitudes and indirectly it only refreshes the interior of Brazil. In this region the heating of increases it to the continent, being led for chains of Southwest of the High northward superior. This revigorates the instability of the continental equatorial mass, whose thunderstorms are, consequently, more needed to the superior cold air that to the proper superficial heating that are, however necessary.

In As the fact the cold mass presents more in force and the Atlantic Polar Front obtains to cover the Mountain range of the Sea and to develop northward, keeping a Northwest-Southeast direction and causing disturbances of the type cold front. So that this happens of December the March, it becomes imperative that it has intense and common renewal of the Atlantic Polar Front, with great fronts, that develops violently until the Bahia (parallel of 15), being soon changed for new formations. Under this intense frontogentica action all the principles suffer violent attraction for the south. The center of action of Travelling Atlantic in the same direction propitiating to the Intertropical Front, with direction East-West, to go down to the Northeast, to win the Chapada of the Araripe and the part occidental person of the Borborema, and arriving with its rains the limit Pernambuco-Bahia. With the winds of the Northwest of the old polar air of the hemisphere North, to adentrar in wedge, until a height of 1.500 meters, under the trade winds of East of the average point of action of the Atlantic, the front invades Par and the coast of the Maranho to the Cear, propitiating inclinations of pressure and rains until Petrolina (elbow of the San Francisco), when cause the rare heavy showers of the Region.