Dust can be carried in the air in several ways, and we class these into 3 main dust event types.
Types of dust events:
Local blowing dust
Local blowing dust
Local blowing dust describes the situation in which soil is eroded by local increases in wind speed. Weather conditions which cause local blowing dust can be associated with cold fronts, troughs or thunderstorms.
Downwind of a dust source region, the dust is transported as a plume. When the dust travels into a location, it is seen as a red or brown haze. The more concentrated the dust is in the air, the harder it is to see- this is called a reduction in visibility.
Large cold fronts and associated troughs can produce large scale dust storms. These large rolling dust-laden fronts are called Haboobs, after dust storms in the Nile River Valley, Egypt.
Recent major dust storms in Australia were on 23 October 2002 and 23 September 2009.
On 23rd of October 2002, a major dust storm crossed the eastern part of the continent. The satellite image shows the extent of the dust plume, from Victoria to the Gulf country of Queensland. An estimated 4.85 million tonnes of sediment was transported during this event, with a large percentage deposited in the Coral Sea.
On 23 September 2009, an even larger dust storm affected eastern Australia. It was nicknamed 'Red Dawn', because the people of Sydney awoke to a red atmosphere on the morning of the 23rd. The storm began on the 22nd in north-eastern South Australia, and continued to the 24th as it gradually moved north east and off the coast of northern Queensland. You can read the news about it or watch the video filmed by the ABC Broken Hill crew as the dust cloud darkened the sky. Read more about major dust storms...
A 'haboob' dust storm in Egypt
Satellite image of dust storm covering eastern Australia, 23 October 2002.