What are they?
Where do they form?
Why are they hazardous?
What impact do they have on people and property?
How do humans respond to the tornado hazard?
What is a tornado?
• A localized and violently destructive column of
air descending from a cumulonimbus cloud and
in contact with the ground
• Not always visible but usually a condensation
funnel develops giving the characteristic tornado
• Can be anything from 100m to 1.6km in
• Tornados can be on the ground 100km or more
in extreme cases
A sequence of images showing the
birth of a tornado. First, the rotating
cloud base lowers. This lowering
becomes a funnel, which continues
descending while winds build near the
surface, kicking up dust and other
debris. Finally, the visible funnel
extends to the ground, and the tornado
begins causing major damage. This
tornado, near Dimmitt, Texas, was one
of the best-observed violent tornadoes
Measuring the Intensity
The Enhanced Fujita Scale
• You need case studies to highlight the
impact on people and property.
• You need to understand and explain the
• Tornados are hazardous because of their
sporadic unpredictable nature - although
the Storm Prediction Centre, Norman
Oklahoma does issue risk category