Mammatus clouds adorned the sky over Wichita, Kansas, on April 30 as a severe storm hit the area. The National Weather Service in Wichita issued several thunderstorm warnings for the area ...

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 ...