9. Cyclonic circulation over Haryana was trigger for dust storm, say experts: A cyclonic circulation over Haryana was the trigger for the deadly dust storm that swept parts of Rajasthan and Uttar Pradesh, weather experts said on Wednesday, estimating that the wind speed during the storm may have gone up to 100 kilometres per hour. The winds were so violent that a number of houses collapsed and electricity poles and trees got uprooted, as the severe dust storm swept parts of these states. The phenomenon was restricted to these two states, largely because of external and domestic reasons, experts said. There were primarily four reasons that lead to the thunderstorm — excessive heating, availability of moisture, instability in atmosphere and a trigger for the storm, India Meteorological Department (IMD) Additional Director General Mritunjay Mohapatra said, according to PTI.