thermal drafts, temperature indifferences between land and sea cause this, eg seabreeze in afternoon caused by warm air off land rising and seabreeze rushing in to fill void, also have opposite in the morning.
If the interior of Australia is like the deserts of the western states, go out to the edge of the desert when the sun comes up, you'll get blown off your feet.
sorry i dunno but now you have asked i wanna know too.
