Education Links
Leaving Cert
Maths
French
English
Chemistry
Physics
Biology
Economics
Spanish
Geography
History
Junior Cert
2. What is a tornado?
Once rotation has begun it extends through the depth of the cloud in the region of updraft. Within a short period of time the updraft becomes concentrated along the axis of the rotation and a column extends from the cloud toward the ground. A measure of the strength of the tornado is often the diameter of the funnel that extends downward. A wide funnel that drops directly to the ground will draw in air from a wide area to feed the storm. The pressure fall near its centre will be immense (particularly given its small size). By contrast, narrow funnels that twist like a rope are usually relatively weak. There are two reasons why the funnel is visible. First, as air enters the low pressure area it expands, cools and water vapour condenses into droplets. Second, and more commonly, the funnel lifts dust and debris into the atmosphere and this swirls around the vortex. Water spouts are tornadoes that form over water and are visible because a column of water is sucked upwards into the cloud - can you imagine the force required to rise a column of water several hundred metres into the air? Not surprisingly, tornadoes are associated with 'freak weather' - rainfalls of fish and frogs, chickens with their feathers plucked off, straw driven into wood, etc..
