We were on holiday on Mykonos and decided to take the morning off touring and find somewhere out of the heat to just sit and read. By 10.30am we were in the bay of Kalafatis on the south-east coast – a nice place to chill out with a long cool drink. We’d only been there fifteen minutes when Lesley noticed that the clouds appeared to be ‘voluming up’ (Cumulonimbus incus). As I was taking photographs, the clouds seemed to suddenly take the form of an exploding atomic bomb. It was so dramatic that everyone nearby stopped what they were doing to look at it.