The two posts on changing the seasons (here and here) resulted
in a lot of interesting information in the comments and it seems
like there is quite a geographical variation in how the seasons
are demarcated, with the US possibly being an outlier in using
the solstices. Reader ahcuah is a kindred soul and has kindly
sent me the data he collected over a full year of the daytime
high and low temperatures. He lives fairly close to Cleveland
and so the data is similar to what I would have gotten. In
general, the shape of the graph and the locations of peaks and
the valleys should be the same over the entire northern
hemisphere (I think) and inverted for the southern, so the
pattern he gets is of far greater general utility than just for
his location. The recorded temperatures are only to the nearest
whole number and this causes a problem for figuring out what the
coldest or warmest days are since there are many days around
those two points that have the same temperature. For example,
the coldest daytime high stays