At the time of writing, while here at home in Norway we are changing winter tires and finding down jackets, many Americans are now scaling the windows and filling tons of bags with sand. The people along America’s tropical east coast are preparing not for winter, but for a powerful and destructive storm; a hurricane. With a wind speed of over 252 km/h, “Milton” is now racing towards Florida’s west coast, and is expected to hit land on Thursday morning Norwegian time. It happens barely two weeks after Hurricane Helene took more than 200 lives in Florida and other states. But what exactly is a hurricane? And do they occur more often now? A boiling pot Rasmus Benestad, senior researcher at the Meteorological Institute, explains that hurricanes are the way the earth sweats. – They absorb moisture and heat from the ground, and then there is a mechanism that removes the heat from the sea surface and gets it up into the atmosphere and away from the globe. It’s a way the earth sweats, he says. It also has similarities to a boiling pot of water, according to the climate scientist. Hurricane “Milton” as seen from the spacecraft “Dragon Endeavor” NOOA via REUTERS – The most effective way to get the excess heat away from a boiling pot of water is for the water to make bubbles, and that’s how nature is screwed up too. And like the bubbles in the kettle, hurricanes start over warm water, sea water mind you. When the ocean surface is very warm, the water begins to evaporate and rise into the air. As the warm, moist air rises, it meets colder air higher up. This causes the warm air to cool and form clouds. Hurricane Helene hit Florida earlier this month. Photo: Kathleen Flynn / Reuters And since the earth spins, the air also begins to spin. As the air spins faster and faster, a storm begins to form. If the storm gets enough warm air and moisture from the ocean, it gets bigger and stronger. And when it gets really strong, we call it a hurricane. So, a hurricane is like a large, spinning storm that gets its energy from warm ocean water. Hurricane categories Hurricanes are classified according to the Saffir-Simpson scale, which divides them into five categories based on wind speed and potential damage Category 1: Wind speeds of 119-153 km/h. Damage to trees and houses may occur. Category 2: Wind speeds of 154-177 km/h. Significant damage to buildings and trees. Category 3: Wind speeds of 178-208 km/h. Major damage to small buildings and extensive destruction of trees. Category 4: Wind speeds of 209-251 km/h. Severe damage to buildings, with some completely destroyed. Category 5: Wind speeds above 252 km/h. Catastrophic damage, with many buildings completely destroyed. Source: Great Norwegian lesson Marine heat wave Hurricanes are not a new weather phenomenon, but are most common in tropical and subtropical areas. The name of the phenomenon depends on where in the world it occurs. Hurricanes that occur in the Pacific Ocean are also known as cyclones and typhoons. Fortunately, hurricanes are rare in Norway, but storms that can reach hurricane force also occur from time to time along the Norwegian coast, especially in the winter. Photo: HANDOUT / AFP But for two hurricanes to hit the same area, and in such a short time as in Florida, is highly unusual, according to Benestad. – It is very unusual for hurricanes to hit roughly the same place. Now there is a marine heat wave, so it is hot in the Caribbean. The violent force must be unleashed, and the hurricane is a mechanism that causes this heat to be unleashed and released into the atmosphere and into space, he says. That both Helene and Milton meet in Florida is accidental, according to Benestad. This is how the town of Blitmore in North Carolina was hit by hurricane “Helene”. MAXAR TECHNOLOGIES VIA AP – You can say it’s bad luck, but Florida is also very vulnerable. That is because it can be hit from all sides, from east, west and south. It is surrounded by sea. Increase in hurricanes According to the UN climate panel, the global number of hurricanes has not increased in recent years, despite climate change. But for the hurricanes that occur in the North Atlantic, the occurrence has become more frequent, and Benestad links the increase precisely to climate change. – Due to global warming, we see that there has been an increase in intense hurricanes and also the amount of precipitation they bring with them, or create, says the climate scientist. Powerful hurricanes Global warming will most likely cause tropical hurricanes to become more powerful, according to the UN climate panel. The reason is that the ocean is warmer than before. New areas may be exposed to remnants of tropical hurricanes. Whether the total number of hurricanes changes is uncertain. Probably there will be the same number or fewer. Swipe to see how a hurricane forms. AFP A hurricane forms Imagine a sea temperature of over 26-27 degrees. The water evaporates and the warm air rises. The air contains a lot of moisture. High up, the air becomes colder, the moisture becomes difficult to retain and a lot of energy is released. If the wind strength is more than 32.6 m/s, we call it a hurricane. AFP Great destruction In a tropical hurricane, the strong winds and enormous amounts of rainfall lead to great destruction. Storm surges and storm surges are also a feared consequence of the hurricane. Already now, increased sea levels are causing both waves and tides to reach further inland. Stronger and more intense hurricanes will lead to more extensive damage. AP Framtiden The American Meteorological Institute (NOAA) believes that an extra number of powerful hurricanes may occur in the Atlantic Ocean this year. Residents in hurricane-prone areas will probably have to get used to both earlier and more powerful hurricanes, according to climate scientists. Hurricanes are also known as cyclones and typhoons in other waters. AP A scale Hurricanes are categorized according to wind strength, where the numbers 1-5 are used. The scale is called Saffir-Simpson. It is category 4 and 5 that we will see more of in the future. Some scientists have suggested that the scale should go to 6, to give more room for hurricanes that grow in size and strength. Hurricanes usually occur in season, but Benestad explains that some studies show that there are more and more before and after the hurricane season. – We see that the number in the North Atlantic has increased. There have never been as many hurricanes observed as in 2020. – We also have our own analyzes that show that when sea areas with temperatures above 26.5 degrees increase and become larger and more extensive, we also get a higher number of hurricanes. Hurricane Ida hit the United States in 2021. Photo: ADREES LATIF / Reuters Photo: ORLANDO SIERRA / AFP Statistics have shown that the ocean temperature must be 26.5 °C or more for hurricanes to occur, and according to the UN, the rate of warming of the ocean has doubled in recent years 20 years. While temperatures in the atmosphere go up and down, the ocean keeps getting warmer, like a pot of water on the stove, the report says. And precisely as Benestad has explained, the ever-increasing sea temperatures have led to an increase in intense hurricanes. Published 09.10.2024, at 19.18
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What is a hurricane? – news Norway – Overview of news from different parts of the country
