With the temperature starting to drop, Gavin Morris explains how the weather mechanism works at this time of year.
“We are now under the influence from cold polar air rather than warm tropical air. Because Australia is in the mid latitude we get weather influences from both.
There is a constant high pressure system over the south pole and wrapping around that is several low pressure systems.
At the roaring forties there are tight isobars causing powerful winds and there is a belt of high pressure caught on the mid latitudes. But the low pressure systems are spinning around clockwise and they are rotating quickly around the south pole.
That part of the globe has been incredibly active and consistent now for the past two weeks, which tells us that this influence of cold air is going to remain.
Because the polar storms are so big, all of that cold air is shooting off them into the upper parts of the atmosphere and through the centre of high pressure systems. That is where cold air falls, that’s
why our nights have been so incredibly icy and there has been sub zero temperatures on the ranges.”
LAST NIGHT’S WEATHER SHOT
Jenny Hill captured these ice stalactites hanging from the water feature in the park at Walcha. Sub zero temperatures have been widespread inland with more frosty nights on the way.
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