A map of Australia shows the locations typically classified as cyclonic or non-cyclonic. The northern coast line near the sea is classified as cyclonic. The northern coast of Australia from Perth to Brisbane, just inland from the cyclonic areas are classified as non-cyclonic.
The terrain category gives a classification for the roughness of the area surrounding the building as obstructions tend to break up the wind. AS 4055 ‘Wind loads for housing’ sets out four terrain categories: TC1, TC2, TC2.5, TC3 with TC3 as the worst case.
A diagram shows a TC1 Residential suburbia well wooded country with less than or equal to 10 houses per hectare. In between each of the seven houses in the diagram there is a tree.
Shielding is about localised effects of the building shape where one part may shield another part from the wind. An open fence has different wind forces than a solid fence.
A picture shows two diagrams of the wind blowing over (and where possible through) a fence. In the first diagram the fence is an open fence (ie there are gaps between the slats in the fence). In the second diagram the fence is a solid fence.
With the solid fence the wind blows over the top and then down quite low, so that it impacts on the walls of the houses on the other side. With the open fence, some of wind passes through the fence and is deflected in different directions on the other side of it. The wind that passes over the fence then flows over the roofs of the houses on the other side.
The shape of the building such as roof pitch and openings in walls affects the pressures that forms around the building. A flat plane shape offers more resistance to wind.