The characteristic shape of hurricanes, cyclones, typhoons is a spiral. There are several types of turns, and determining the characteristic equation of which spiral the “cyclone bomb" (CB) fits into is the goal of the work. In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. An “explosive extratropical cyclone" is an atmospheric phenomenon that occurs when there is a very rapid drop in central atmospheric pressure. This phenomenon, with its characteristic of rapidly lowering the pressure in its interior, generates very intense winds and for this reason it is called explosive cyclone, bomb cyclone. It was determined the mathematical equation of the shape of the extratropical cyclone, being in the shape of a spiral called "Cotes's Spiral." In the case of CB, which formed in the south of the Atlantic Ocean, and passed through the south coast of Brazil in July 2020, causing great damages in several cities in the State of Santa Catarina. With gusts recorded of 116 km/h, atmospheric phenomenon – CB hit southern Brazil on June 30, the beginning of winter 2020, causing destruction in its influence over. In five hours the CB traveled a distance of 257.48 km (159.99 miles), at an average speed of 51.496 km/h (31.998 miles/h) 27.81 knots, moved towards ENE, with a low pressure center of 986 mbar, 07:20 UTC, approximate location 35ºS 45ºW, and 5 hours after 12:20 UTC had already grown and had a low pressure center of 972 mbar , approximate location 34ºS 42º30'W.