The four bases of dating
One finds disagreement on the starting dates of the seasons at both the scientific and the lay level.
There are however three basic ways in which starting dates may be assigned.
Most analysis of climate is done using the assumption that January is mid-summer and July min-winter.
The instances at which the solstices and equinoxes occur can be accurately calculated.
Moreover, expressions such as spring equinox and summer solstice are no longer used in astronomy.
Instead, the four astronomical instances are identified as the ascending and descending equinoxes in March and September respectively, and the northern and southern solstices in June and December.
A climatologically definition of the seasons would obviously be more realistic.
Earlier astronomical textbooks often defined the four seasons as starting on the dates of the corresponding equinoxes and solstices.
But more recent books avoid defining the seasons in any way: two new editions of earlier books have in fact deleted their previous definitions.
South Africa does not really experience four distinct seasons.
Throughout South Africa the transitional seasons of Autumn and Spring tend to be very short.
In the temperate latitudes of Europe and North America the climatological seasons are conventionally defined as shown in Table I.