Usually winds do not have a large influence on what we do. Winds are really only important when they become very strong and give gales or worse. The most severe windy conditions happen with tornadoes and hurricanes.

A tornado comes from the Spanish ‘tronada’, or thunderstorm. Tornadoes are tightly spinning, funnel-shaped clouds that appear to hang from the bottom of a thundercloud.

The winds in the centre of the funnel are the fastest in the world, some reaching 800 km/hr. They quickly pass over the ground, but the destruction they can cause in just a few minutes’ passage can be tremendous.

The size of a tornado
Tornadoes are produced as air is sucked very quickly into the bottom of a thunderstorm. They can form over land or water (where they are called waterspouts).

Tornadoes may be just a few tens of metres across where they touch the ground; the biggest are only some hundreds of metres across. They may last for less than an hour, and may travel just a few tens of kilometres.

Inside a tornado the air is very ‘thin’ (it is an area of very low pressure). Many buildings that have been tightly shuttered for protection often explode as a tornado passes because the air pressure inside the building remains much greater than that on the outside.

Tornadoes are very much smaller than hurricanes. You find tornadoes from the cool lands of the United Kingdom to the warmer areas of Australia, but they are by far the most common in the United States, which holds the world record at an average of 1,000 each year, most causing damage between May and July.