Where is the hot air for Australia's record spring heatwave coming from?
There are 2 causes of record high daytime temperatures: insolation and subsidence. As air is forced to subside, heat of compression adds to insolation. This happens at the poleward margins of the tropical Hadley cells, at or near the latitude where the deserts of Australia are located. Cloud cover (or dustiness in deserts) contributes to record high nighttime temperatures by trapping infrared radiation from the Earth.