A real thunder type summer sky seen today in Surrey and Sussex with
altocumulus almost of the castellanus variety and a sultry feel to the early
afternoon. In summer it would have been a hot day breaking down to
widespread storms. I wish I had kept a record of such days over the years to
see any pattern to the first date of a thundery sky observed. Must have a
more detailed look at my records.

Ian Currie, Coulsdon.
www.frostedearth.com