On Monday, 19 August a sizable dust devil spun sand and dust in a swirling vertical cloud that ran along the side of a dirt road outside the town of Emalahleni (Witbank), about 100km from Pretoria.
Pamela-Ann Leissner filmed the twister and shared the footage with Storm Report SA. According to World Atlas, ‘Dust devils are generally harmless, but on rare incidences, they can be huge enough to pose a threat.
‘These whirlwinds can be as small as 3m in width and on average can measure up to 30m wide, with a height of up to 200m’ (a few have even measured up to 1km in height), according to the American Meterological Society.
Dust devils are usually not dangerous but can cause significant danger to paragliders and skydivers. They often dissipate in less than a minute but on rare occasions, ‘they can reach a diameter of nearly 300 feet [91m] with the wind spinning at about 60 miles[96km/h] per hour and can last for up to twenty minutes,’ reports World Atlas.
How do dust devils form?
Rotating columns of air can occur when one piece of ground heats up faster than the ground surrounding it, causing a mini-low pressure system. The difference in temperature, with the hot air rising and cool air sinking can make the air unstable. They usually occur in dry places, with little or no wind.
Image credit: Pamela-Ann Leissner via Storm Report SA
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