Scientists, meteorologists and storm chasers try to uncover the secrets of F5 tornadoes, the largest, most powerful and most dangerous on Earth. Included are looks at how funnels form and the devastating 2003 tornado in Moore, Oklahoma, plus "tornado tourists", who pay companies to take them to the ferocious phenomena to see them first-hand.

NOVA Season 31 Episodes...

• s31e01 - Infinite Secrets
• s31e02 - Who Killed The Red Baron?
• s31e03 - The Elegant Universe: Einstein's Dream (1)
• s31e04 - The Elegant Universe: String's The Thing (2)
• s31e05 - The Elegant Universe: Welcome To The 11th Dimension (3)
• s31e06 - Wright Brothers' Flying Machine
• s31e07 - Magnetic Storm
• s31e08 - Volcano Above The Clouds
• s31e09 - MARS: Dead Or Alive
• s31e10 - Secrets Of The Crocodile Caves
• s31e11 - Dogs And More Dogs
• s31e12 - Descent Into The Ice
• s31e13 - Crash Of Flight 111
• s31e14 - Life And Death In The War Zone
• s31e15 - Hunt For The Supertwister
• s31e16 - World In The Balance: The People Paradox (1)
• s31e17 - World In The Balance: China Revs Up (2)
• s31e18 - Battle Plan Under Fire

NOVA Show Summary

Seen in more than 100 countries, NOVA is the most watched science based television series in the world and the most watched documentary series on PBS. It is also one of television's most acclaimed series, having won many major television awards, most of them many times over.