BBC film crew chase tornado in Colorado

18 March 2012 Last updated at 04:36 ET Help

Scientists are getting to grips with the mechanisms behind extreme weather events such as tornadoes.

Dr Helen Czerski visited the US state of Colorado - part of the area known as Tornado Alley - to investigate how tornadoes form with the help of atmospheric scientist Josh Wurman.

No two tornadoes are the same, but they all need certain conditions to form - in particular intense heat.

The final episode of Orbit: Earth's Extraordinary Journey is on BBC2 at 2100 GMT on Sunday 18 March and is available online afterwards on the BBC iPlayer.

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