Between the areas of high and low pressure winds form the patterns shown in Figure 1. The circulation of these winds and the passage of high and low pressure cells have a major influence on Australia's climate at different times of the year. Points to remember The sun warms the earth's surface and this warms the air above. The earth's surface is warmed most near the equator, and least at the poles. The air above land is warmed more than that above water.
Winds occur because the atmospheric pressures try to 'even themselves out'.
The rotation of the earth causes the high and low pressure wind spirals. In the southern hemisphere, air from high pressure systems spirals anticlockwise and outwards, but spirals clockwise into low pressure systems. Thus, in December, when the southern hemisphere is tipped towards the sun, more direct sunlight and long hours of daylight cause warmer weather than in June, when the southern hemisphere is tipped away from the sun. Resources and Actions Class discussion Use the following information and questions to have a class discussion. Modify lesson as required.