A giant mushroom cloud has just appeared in the sky over Mykonos, Greece.
Mushroom cloud.
At first glance it looks like the result of nuclear weapons testing in the South Pacific in the 1940s and 1950s.
In fact, these clouds are the result of the sudden formation of giant low-density, hot air currents near the ground.
The hot air rises rapidly and moves in a turbulent, swirling motion, carrying smoke and debris to form mushroom stems and then mushroom caps.