Sometimes very ominous in appearance, Mammatus clouds are harmless and do not mean that a tornado is about to form - a commonly held misconception. In fact, mammatus are usually seen after the worst of a thunderstorm has passed.
Thick fog creates a 'tsunami' of wave clouds on a beach in Florida, US. The phenomenon was snapped by pilot JR Hott, from Panhandle Helicopters, as he flew over a fog-swamped beach in Florida on Sunday February The fog wave engulfed an entire row of ta
lenticular clouds over Yorkshire, England. Lenticular clouds (Altocumulus lenticularis) are stationary lens-shaped clouds that form in the troposphere, normally in perpendicular alignment to the wind direction.