I live in a sub-tropical region of Australia.

Earlier today, we experienced temperatures of 31C and it was clear about 2 hours before I went out and noticed the following clouds directly above my house - the entire sky either has this or is very grey.

There is a constant background of thunder and distant lightning is observed - the wind is picking up a bit, though still a breeze. No rain at this stage.

enter image description here


1 Answer 1


These are mammatus clouds. The signify instability (via negative buoyancy, convective mixing, entrainment or other sources) at the cloud base which causes the bulbous udder-like structure. As in your case they can often be observed in association with strong convection.

  • $\begingroup$ The sky is getting very dark now - I suspected that they were mammatus - thank you for that! $\endgroup$
    – user4727
    Nov 8, 2015 at 2:44
  • $\begingroup$ Just to confirm that it is mammatus. Such cloud formations generally don't last for long because of the inherent instability of their formation. Nice photo, by the way. $\endgroup$ Nov 8, 2015 at 6:37

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