Much of the weather that has affected Australia over the past week was associated with cyclonic vorticity. So what is vorticity? We give you the low down in this week's #WeatherWordWednesday. Vorticity is a measure of the rotation of the air associated with weather systems. In the Southern Hemisphere, air rotates clockwise around low pressure systems, troughs and cold fronts and is described as having negative (or cyclonic) vorticity. Air rotates counter-clockwise around high pressure systems an