In accordance with Mendona (2007), the ticket of a system frontal is marked by the atmospheric disturbance, being to the times provoked for the expulsion of hot air, originating the front oclusa. Blacksmith (2006) affirms that, to the times the orografia can cause the retardation of a warm front or cold, becoming it stationary, that is, it loses its force and starts to move itself slowly. The fronts are classified in front Arctic/polar Antarctica and fronts. Thus, the Arctic front/Antarctica occurs through the contact of the polar air masses, mainly in the winter. Already the polar front that is strong active, separates the polar air of tropical air. This front is divided in: cold front and warm front. They characterize the dynamism of the atmosphere, therefore she exerts considerable thermal contrasts, what she determines the succession of the types of time. Of this form, the Atlantic polar front (FPA) represents great importance in the definition of the types of time and in the climatic configuration of the South America, mainly in Brazil.
Thus, the Atlantic polar mass (MPA) when reaching the south coast of Brazil, is joined with Atlantic tropical mass (MTA) it provokes much folloied rain of winds, the times extends itself arriving until the Amazon region provoking the phenomenon friagem. Cold Frente For Mendona (2007) a cold front occurs when a cold air mass that denser and more is weighed advances in direction to a hot air mass, pushing it for top and front, compelling to leave it the area, either for rise or advection. In accordance with Blacksmith (2006), it well is defined, with multiple cloud layers and when it passes for one determined region, dense and cold air takes the place of the hot air, that is forced to go up quickly, causing the cumuliformes cloud appearance. Thus, this front provokes many thunderstorms that can be folloied by hail and gust winds.