Why is the United States the tornado capital of the world?

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Each year, the United States receives about four times as many tornadoes as the rest of the world combined.

The tornadoes that swept through six states in the United States on December 10 were among the deadliest on record, with at least 90 deaths.

Hardest hit has been Kentucky, which has reported at least 80 deaths, and several more have been reported in Arkansas, Illinois and Tennessee. This would make the event not only one of the most devastating in Kentucky history, but The history of the United States, and potentially the deadliest December epidemic on record.

When it comes to tornadoes, the United States grapples with weather exceptionalism compared to the rest of the world, and by a significant margin.

As a perspective, countries outside of the United States witness about 200 to 300 tornadoes per year, while in the United States that number is well over 1,200 per year.

It is four times as many tornadoes as the rest of the world combined.

What makes the United States so prone to tornadoes?

Most tornadoes in the United States occur in the Great Plains – notably known as “Tornado alley”- a perfect area for twisters. It is generally considered to be an area that stretches from northern Texas, Oklahoma, Kansas, Colorado, Nebraska to South Dakota.

The main reason for this is geography. The central part of the United States is unique in that there is a large area of ​​warm water just to the south (Gulf of Mexico) and a high mountain range (the Rocky Mountains) that runs north to south. .

A tornado requires a few special ingredients that Tornado Alley is full of: hot, humid air at low levels, cold, dry air at higher levels, and a mechanism to lift that hot air.

Much warm, humid air flows over the plains of the Gulf of Mexico, and cool, dry air flows from the Rocky Mountains to the west. Eventually, a change in temperature or pressure will occur and lift this warm air into the cold air, forming an updraft (an upward movement of air).

Once they meet, the moisture in the warm air begins to condense, forming clouds and the start of a thunderstorm.

Under normal conditions, rain would fall from these clouds and cool the hot air, breaking up the storm. But in Tornado Alley, there is a strong current of air flowing from west to east, known as the Jet stream. This, along with the cool mountain air, drives the rain away, keeping the air warm and humid in the updraft, allowing the storm to intensify.

For a storm to spin next, the winds have to move at different speeds and in different directions, and Tornado Alley has them in abundance.

Air from the Gulf moves slowly across the plains. Meanwhile, the mountain jet stream provides a constant flow of high and rapid air flowing eastward. Because the jet stream flows faster and in a different direction, it spins the gulf, when it is below, like a spinning soccer ball. As the rotating air is drawn into the updraft, it is tilted but continues to rotate, causing all of the updraft to spin.

Storms like this are known as “supercells”And they create ideal conditions for tornadoes. They are rare, but most often occur in Tornado Alley.

As the supercell grows, the spiral updraft begins to stretch towards the ground and forcefully sucks air into the cyclone. Air rushes in from the sides and a spinning cloud of dust forms below, which brings us to the final step – routing the vertically rotating air towards the ground.

As the air is sucked in, the pressure increases and the faster and longer the tornado. It stretches closer to the ground until it finally meets this cloud of dust. And then it hits the ground.

In Oklahoma, known as the tornado capital of the world, winds have already reached a staggering 400 kilometers per hour.

However, many scientists and experts in recent years have warned that the inhabitants of the south of the country are just as exposed to tornadoes as those of the plains.

To research reveals that as the planet warms, Tornado Alley is starting to move east through the Mississippi River Valley, as evidenced by last week’s deadly tornado that hit the southern states.

Outside of the United States, southeastern Brazil and northeastern Argentina contain some of the same ingredients as Tornado Alley: cool mountain air from the Andes and hot, humid air from there. ‘Amazonia.

Another is Bangladesh, where warm, humid air travels from the Bay of Bengal and heads north, where it overlaps the winds blowing southeast from the Himalayan mountains.

With an average of around six tornadoes per year, Bangladesh also experienced the world’s deadliest tornado in 1989, which killed 1,300 people and injured 12,000.

Source: TRT World


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