photo #6128904

Kelly is a flight nurse with the Aeromedical Operations service of New South Wales Ambulance in Australia and the daughter of Carol Drew (Member 29,358). Kelly and the other members of her medical team were flying down the New South Wales coast to collect a patient when their pilot pointed out an unusual cloud off the shores of Shoalhaven. This was a rare roll cloud, known more formally as Stratocumulus volutus. It can form over coastal waters, when opposing sea breezes collide with each other and set off a wave that travels through the air just over the water. The promontory known as Beecroft Peninsula just visible to the right of the image might have been the cause.As it was heated by the Sun earlier in the day, it might have caused the air over it to expand and lift, pulling in breezes from the cooler waters on either side. Wind conditions need to be just right, as does the air’s moisture content. Only when there’s enough humidity can the cooling of the lifting air in the middle of the travelling wave condense into droplets that appear as a long roll cloud moving across the waters. ‘Kelly didn’t realise how special the formation was,’ said Carol, who knew exactly what it was when she received it. ‘Kelly shared the photo with me,’ she beamed, ‘because she knows how much I love clouds.’