Autumn is normally associated with dropping temperatures and the nights drawing in as winter approaches.
There are two different dates when Autumn could be said to begin. Autumn as defined by the Earth’s orbit around the sun, begins on the Autumn equinox which falls on 22 or 23 September.
However, for the purposes of recording climate data, it is important to have set dates that can be compared, so the meteorological Autumn always begins on 1 September.
The word equinox comes from the Latin equi (meaning equal) and nox (meaning night) accounting for the equinox marking the time when day and night are of equal length.
We often notice the nights begin to draw in from this point as after the Autumn equinox, the night longer than the day, until this is reversed at the Spring equinox.
One of the most stunning signs of Autumn is the turning of the leaves. The shorter days are a sign to trees to begin to prepare for winter.
During winter there is not enough light for photosynthesis to occur, so as the days shorten throughout Autumn, the trees begin to close down their food production systems and reduce the amount of chlorophyll in their leaves. The most vibrant displays of autumn leaves are evident when a dry summer is followed by an autumn with dry, sunny days and cold, but not freezing, nights.
Autumn according to the meteorological calendar begins in September and ends in November. In the astronomical calendar, the beginning of autumn is marked by the autumn equinox which occurs around the 22 September.
During the autumn equinox the sun shines directly on the equator and day and night around the globe are of almost equal length – a day and night of roughly 12 hours each.
In Greek mythology, Autumn began when Persephone was abducted by Hades to be the Queen of the Underworld. In distress Persephone’s mother, Demeter (the goddess of the harvest), caused all the crops on Earth to die until her daughter was allowed to return, marking Spring.