Formed by cold air sinking down, mammatus clouds are usually seen when there is turbulence in a cumulonimbus cloud. Two astronauts are returning home after nine months in space. Nick Beake of the ...

Keen photographer Garry Hornby spotted them above Huntington in York and posted: "Stunning mammatus clouds over Huntington road this morning." Fellow club member Kieran Delaney also shared a photo ...