A Dust Storm occurs when loose dust particles are lifted by a stong wind. This wind can be from a Thunderstorm gust front, or can be from a dry Cold Front.
If dust is blown off the surface and reduces visibility to less than 1000m, this is referred to as a dust storm.(Wagtendonk et al., 2003)
"The vertical extent of the dust or sand that is raised is largely determined by the stability of the atmosphere above the ground as well as by the weight of the particulates."(Wikipedia, 2009.) Some dust storms have extended to 20,000 feet in height.
"Drought and wind contribute to the emergence of dust storms, as do poor farming and grazing practices by exposing the dust and sand to the wind". (Wikipedia, 2009.)
There will always be strong winds associated with a dust storm, as well as very poor visibility. This makes taking off and landing difficult, if not impossible. Dust storms usually cause major delays at airports when they occur.
Sydney, September 2009
The combination of a drought caused by the El Nino effect and a stong low and cold front sweeping from West to East across Australia caused a wide spread dust storm, which affected flight operations across the east coast of Australia on the 23rd of September 2009. The dust in this case had a red tinge, causing the sky to glow red during the storm.
The Sydney Harbor Bridge at 10AM, Image Embedded from Daily Mail UK on 24th September 2009