HURRICANE SEASON: THE MOST VIOLENT STORMS ON EARTH

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We explain how hurricanes are fueled, monitored and the damage caused by 3 of the most violent storms of the 21st century

Words: Aleksandra Georgieva

Photography: Andrew Seaman, Giancarlo Revolledo

10 September 2019

The scientific term for the violent storms, known as hurricanes, is tropical cyclones. Hurricanes form only over the eastern Pacific Ocean or over the Atlantic Ocean. The 2019 Atlantic Hurricane Season officially started on April 4th and is expected to end on November 30th. So far there were 13 storms that have been predicted, 5 tropical cyclones and 2 hurricanes which caused significant destruction - Barry (category 1; approximate amount of the damage: $600 million) and Dorian (category 5; approximate amount of the damage: $7 billion).

Arguably, global warming could be given as the main reason the recent hurricane seasons have been more destructive than before. This would be due to the fact that there has been a gradual increase in the temperatures of the global oceans and air. Yet, this has not been scientifically proven. This is why, we are taking a closer look into how tropical cyclones are formed and which hurricanes have been named the most destructive storms of the century.

 

A Recipe for Disaster

Hurricanes require specific conditions to occur, such as thunderstorm activity that creates ocean heat. The water temperature over a depth of at least 50m must reach a minimum of 26.5°C. Such devastating storms can be weakened when the surrounding area has a large difference in the direction and the wind speed.

 

Hurricane Formation

Often beginning as tropical waves, hurricanes form the same way. Air from low pressure areas begins to move through moisture-rich tropics. Tropical cyclones use warm waters as fuel, which is why hurricanes only occur near the equator. Due to the Earth's rotation on its axis, the storms that form south of the equator spin clockwise and the hurricanes north of the equator have a counterclockwise spin.

 

When the warm, moist air over the ocean rises upward and away from the surface it causes areas of low air pressure below. The surrounding air has higher air pressure until it pushes into those low-pressure areas where it becomes moist and warm and starts to rise too.

 

When this process repeats more and more surrounding air swirls in. The warm air above the ocean surface begins to cool down and water evaporates, creating clouds and thunderstorms. Storms gather power as the ocean’s heat swirls the clouds and powers the winds. High pressure air flows towards the very calm and clear centre.

Storm Types

Tropical storm occurs when the winds in the rotating storm spin with the speed of 39 mph.

Tropical cyclone (or hurricane) happens when the wind speed reaches 74 mph.

 

Facts and Figures

There are two GOES satellites, built by NASA and operated by the National Oceanic and Atmospheric Administration (NOAA). Their purpose is to detect hurricanes by predicting weather forecasts and giving warnings from 22,300 miles above the surface of Earth.

 

Tropical cyclones weaken by reaching land as the warm ocean water is no longer near to fuel them. However, they are often powerful enough to bring severe rain and to cause damage far inland before dying down. Hurricanes are globally referred to as the most violent storms on Earth.

 

Did you know that: The fury of the winds during a single hurricane can channel equal energy as the electrical generating capacity of the entire world.

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3 of the Most Violent Storms of the 21st Century
 

  • Katrina was a 2005 Category 5 hurricane, which caused catastrophic death and destruction. The storm was particularly deadly in New Orleans and other parts of the Gulf Coast where engineering flaws in the cities’ flood protection system lead to the loss of many lives. On August 26 Katrina looked like it was losing strength, until the warm water in the Gulf rapidly fuelled a storm. By August 28 the residents of New Orleans were facing a Category 3 hurricane and mandatory evacuation. The floods left locals trapped in their homes and 40% of the deaths were the result of drowning. By the time Katrina died out, 80% of New Orleans was underwater and 1,833 people had lost their lives. The Federal Emergency Management Agency described it as "the single most catastrophic natural disaster in US history"
     

  • Sandy started as a slow-moving storm. It passed through Jamaica, Cuba (turning into a Category 3 storm) and Haiti before it decreased in strength. It was the deadliest and most destructive hurricane of 2012. It took the lives of at least 233 people in the 8 countries it passed through. In October 2012 when Sandy reached the United States, it had turned into a post-tropical cyclone. It caused serious damages to beaches in Queens, to Staten Island and the Jersey Shore. “Superstorm Sandy” flooded areas of lower Manhattan and left locals without power for days. When it got to New York City, it resembled a winter rather than a tropical storm.
     

  • Maria was the second Category 5 hurricane of 2017. Just two weeks after the devastating Irma, it raged through some of the same areas. On September 18 hurricane Maria brought destruction to the small island of Dominica. It passed through Guadalupe and the U.S. Virgin Islands before weakening to Category 4. Still, the 155mph of winds and the 10 inches of water destroyed the island of Puerto Rico on September 20. After a while 90% of the island was lacking electricity and the recovery process was very slow, while some citizens moved to the US mainland permanently. An entire year later, in 2018, an independent investigation concluded that the death toll of hurricane Maria had reached 2,975 people.

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