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Engage: Cyclone Testing Station
What causes cyclones?



What is a Cyclone?

Cyclones are giant, spinning, whirlwind storms. They are called hurricanes in North America and typhoons in Asia. In order for a cyclone to be identified as a cyclone, it must be travelling over 119 km per hour and it must have been formed over the ocean in a tropical region. Here is a table that classifies cyclones by their strength. There are five categories: Category 1 is the weakest and Category 5 is the strongest.

Cyclone categories and severity, courtesy of the Australian Emergency Management Institute
Category Wind Gusts Ocean Swells Damage
1 Up to 125 km/hr – Gales 1.2 – 1.6 m Slight damage Trees and farmland damaged.
2 126 – 169 km/hr – Destructive 1.7 – 2.5 m Significant Damage Minor house damage. Severe damage to signs and trees. Heavy damage to crops
3 170 – 224 km/hr Very Destructive 2.6 – 3.7 m Structural damage House roofs and most likely power failures
4 225 – 279 km/hr – Very Destructive 3.8 – 5.4 m Significant roofing and structural damage Airborne debris, widespread power failure
5 Winds above 280 km/hr – Very Destructive More than 5.5 m Almost total destruction and extremely dangerous Houses flattened, cars overturned

As you can see, these great storms are usually dangerous and can cause damage to everything in their path. During such events, everyone is advised to seek shelter in their homes or evacuation centers.

However, are we sure these buildings are up to the task of resisting potentially 300 km/h winds?

The architecture of a house, especially the way a roof is designed, plays a part in the amount of damage sustained from strong winds. The two types of roofing tested in this experiment are a gabled roof (left) and the lean-to (right).

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Model house with a gabled roof (left) and a lean-to roof (right).

Below on the left there is a clip of a testing station showing the roof of a house lifting off in strong winds. On the right we have a clip showing the wind forces all over the roof.

As mentioned above, the differing geometry of these houses will determine the effect strong winds have on them and you will have the chance to explore this in the next section.