Tornados form from rotating columns of air that descend from cumulonimbus clouds and touch the ground. They range from 100 meters to 1.6 kilometers in diameter and can travel over 100 kilometers. Tornados primarily form in the central United States due to clashes between warm and cold air masses. They are hazardous because of their unpredictable nature and ability to cause severe damage to people and property quickly. Humans have developed warning systems and the enhanced Fujita scale to measure tornado intensity to help respond to the tornado hazard.

1. Tornados
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?

2. 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
formation
• Can be anything from 100m to 1.6km in
diameter
• Tornados can be on the ground 100km or more
in extreme cases

5. Global Distribution

6. Where do they form - USA?

7. A Little More Detail

8. But Why?
Its all due to different air masses.

9. And How?

10. 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
in history

11. Inside – What is it like?

12. Go to this website for a cool animation

13. Measuring the Intensity
The Enhanced Fujita Scale

14. Don’t Forget
• You need case studies to highlight the
impact on people and property.
• You need to understand and explain the
human response.
• Tornados are hazardous because of their
sporadic unpredictable nature - although
the Storm Prediction Centre, Norman
Oklahoma does issue risk category
warnings -

15. And then there is the storm chasers!