Tornado outbreaks become more common in US

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Tornado outbreaks become more common in US

Tornadoes are among the most destructive types of storm.These twisters of wind have killed more than 1000 people in the U.S. over the past two decades. Now, a new study shows tornado outbreaks are becoming more frequent.

CCTV’s Asieh Namdar reports.

Tornado outbreaks becoming more common in US

Tornadoes are among the most destructive types of storm.These twisters of wind have killed more than 1000 people in the U.S. over the past two decades. Now, a new study shows tornado outbreaks are becoming more frequent. CCTV’s Asieh Namdar reports.

A 1.5 kilometer wide tornado rips through the city of Joplin in Missouri in May, 2011.

Winds topped 320 kilometers per hour. Businesses, homes, even a hospital were all destroyed. 158 people died. In the end, damage was estimated at nearly $3 billion.

And just weeks earlier in Tuscaloosa, Alabama, 65 people were killed in a tornado that carved a path through nearly 130 kilometers (80.78 miles).

It was part of what was dubbed a “super outbreak”-one of the worst tornado outbreaks in U.S. history.

Over the course of three days, the southeastern United States saw 349 separate tornadoes.

United States; US National Weather Service; NOAA; 1995 to 2016

The statistic shows the number of tornadoes in the United States from 1995 to 2016. In 2014, around 886 tornadoes were reported in the U.S.

A study published this month in the journal “Science” said these so-called “tornado clusters” are becoming more common.

Fifty years ago there were 40 outbreaks per year. Last year, the number doubled to 80.

The authors of the study don’t know why, but say it’s a trend. They add that it does not appear to be linked to climate change.

What we do know is how tornadoes form: when hot humid air typically from the sea meets dry and cold air typically from the poles, the hot air rises. And the cold air gathers underneath, causing thunder clouds to form.

The two air masses begin rotating around each other and a funnel appears. When it touches ground, it’s officially a tornado.

Tornadoes are measured on the “Enhanced Fujita Scale”, going from zero to five.

An E-F zero is relatively weak with winds between 105 and 137 kilometers (65.24-85.13 miles) per hour. They cause minimal damage.

On the other hand, an E-F five tornado is extremely strong with winds ranging from 320 to 500 kilometers (198.84-310.69 miles) per hour. These winds are strong enough to pull entire houses off their foundations.

While tornadoes can form all over the world, the U.S. is most prone by far, especially an area known as “Tornado Alley” in the country’s Midwest.


Bob Henson discusses global climate change

The impact of climate change is being felt all around the global and causing many changes for millions of populations. To discuss the various observable changes linked with the global climate, CCTV America’s Asieh Namdar spoke with Bob Henson, weather and climate science blogger for Weather Underground.