Rio Grande do Sul faces flooding, hailstorms and even a tornado A tornado hit three municipalities in the northwest of Rio Grande do Sul in the early evening of last Tuesday (28), leaving seven people injured and a trail of destruction. The gusts of wind ripped houses apart, knocked down trees and poles and also left injured animals. According to the state's Civil Defense, the tornado occurred at around 6:25 pm and was identified by images from the meteorological radar of Chapecó, in Santa Catarina, more than 200 kilometers away. The phenomenon was generated by a supercell, a type of intense storm that can cause large hail, strong gusts of wind and, in some situations, tornadoes. ?? But, after all, what is a tornado? What does it mean to say that it emerged from a supercell? And what is the difference between these phenomena and a cyclone and a hurricane? Although they are related, they are not the same thing. There are important differences in the scale, duration and way in which each one develops: ? Scale: the tornado is a smaller phenomenon and usually hits a narrow range. A storm or cyclone can spread over hundreds of kilometers. ?? Duration: tornadoes usually remain on the ground for a few minutes. A storm can last for hours, while a cyclone can last for several days. ? Power: despite being small, the tornado concentrates very intense winds in a limited area. Therefore, it can destroy one house and leave another, located a short distance away, practically intact. ?? A supercell, in short, is a storm that features a rotating air current inside the cloud. This type of formation can generate heavy rain, hail, wind and tornadoes. ? The cyclone, in turn, is a much larger system, formed by an area of ??low atmospheric pressure. It can contribute to the formation of severe thunderstorms, but it is not a giant tornado. ? Hurricane is the name given to tropical cyclones that hit a specific region of the planet. Only one hurricane has hit South America so far: Catarina, in 2004. It left 11 people dead and caused significant damage in the south of Santa Catarina. But, for the sake of comparison, winds of 200 km/h were recorded at the time. ? Are tornadoes rare in Rio Grande do Sul? They don't happen often, but they aren't unknown in the state either. The south of Brazil has conditions that can favor severe storms, especially when hot, humid air meets a mass of cold air. Understand below: What tornadoes are; What are extratropical cyclones; What are tropical cyclones, or hurricanes; And are they really becoming more frequent in Brazil? Resident records tornado in Giruá, RS Image courtesy/ Renan Bayer 1. Tornado ?? Tornadoes are minor, but very intense, atmospheric phenomena. They generally arise from severe storms in areas with large wind variations. What happened in Rio Grande do Sul was that: a cold front advanced through the state and encountered a hot and humid atmosphere; this meeting favored the formation of very heavy storm clouds; inside one of these clouds, an air current began to rotate and gave rise to a supercell; the rotation intensified and a funnel descended from the base of the cloud; When this funnel touched the ground, it was classified as a tornado. Meteorology can identify when there are favorable conditions for severe storms, but it is not yet possible to accurately indicate the point at which a tornado will form or touch down. The cloud that gave rise to Tuesday's tornado is called a supercell. ?? Supercell is a type of storm characterized by the presence of a mesocyclone, an ascending and rotating air current located inside the cloud. While a cyclone can be hundreds or even more than a thousand kilometers long, a tornado is usually a few tens or hundreds of meters wide when it touches down. 2. Extratropical cyclone ?? Cyclones are all low atmospheric pressure systems. They "pull" hot, humid air from the surface and throw it upwards, forming rain clouds. So-called extratropical cyclones move air masses of different temperatures, that is, hot and cold. They appear in the planet's mid-latitudes, outside the tropical zone, such as in the South Atlantic (the coast of southern Brazil). Warm, moist air over the ocean rises, creating the low pressure area. Air from surrounding areas, with higher pressure, moves into this area, warming and rising as well. As warm air rises and cools, it forms clouds. And when they appear in warmer regions, the tropical ones? This is where the phenomena we know as hurricanes or typhoons occur. 3-year-old girl went to her grandfather hours before a tornado destroyed her house in RS 3. Tropical cyclone (hurricane and typhoon) Hurricanes, typhoons and cyclones are storms that receive different names, according to the region of the globe in which they occur. In the north of the Atlantic Ocean and the northeast of the Pacific, they are called hurricanes. When they appear in the northwest of the Pacific Ocean, they are called typhoons. Finally, the cyclone is the storm formed in the southern Atlantic, the South Pacific and the Indian Ocean. Tropical cyclones only form in warm ocean waters close to the Equator, at least 30° latitude north or south of the line, where the sea temperature is at least 27ºC. Warmed waters are precisely what favors the strengthening of hurricanes in the Florida region, in the United States, for example. In summary: Tropical: also known as hurricanes or typhoons, which form in equatorial regions, over the oceans, and derive their energy from the heat extracted from the seas; Extratropical: they appear preferably in mid-latitudes and are formed by the contrast in temperatures of different air masses (hot and cold); Subtropicals: have characteristics of both previous ones. Typically, they form when an extratropical cyclone develops over the