Autumn (also known as fall in American English) is one of the four temperate seasons. Autumn marks the transition from summer into winter, usually in March (Southern Hemisphere) or September (Northern Hemisphere) when the arrival of night becomes noticeably earlier.
The equinoxes might be expected to be in the middle of their respective seasons, but temperature lag (caused by the thermal latency of the ground and sea) means that seasons appear later than dates calculated from a purely astronomical perspective. The actual lag varies with region, so some cultures regard the autumnal equinox as â€œmid-autumnâ€ whilst others with a longer lag treat it as the start of autumn. Meteorologists (and most of the temperate countries in the southern hemisphere) use a definition based on months, with autumn being September, October and November in the northern hemisphere, and March, April and May in the southern hemisphere.
Autumn starts on or around 8 August and ends on about 7 November in traditional East Asian solar term. In Ireland, the autumn months according to the national meteorological service, Met Ã‰ireann, are September, October and November. In Australia, autumn officially begins on 1 March and ends 31 May.
The word autumn comes from the Old French word autompne (automne in modern French), and was later normalised to the original Latin word autumnus.
Before the 16th century, harvest was the term usually used to refer to the season. However, as more people gradually moved from working the land to living in towns (especially those who could read and write, the only people whose use of language we now know), the word harvest lost its reference to the time of year and came to refer only to the actual activity of reaping, and autumn, as well as fall, began to replace it as a reference to the season.
The alternative word fall is now mostly a North American English word for the season. It traces its origins to old Germanic languages. The exact derivation is unclear, the Old English fiÃ¦ll orfeallan and the Old Norse fall all being possible candidates. However, these words all have the meaning â€œto fall from a heightâ€ and are clearly derived either from a common root or from each other. The term came to denote the season in 16th century England, a contraction of Middle English expressions like â€œfall of the leafâ€ and â€œfall of the year.â€
During the 17th century, English emigration to the British colonies in North America was at its peak, and the new settlers took the English language with them. While the term fall gradually became obsolete in Britain, it became the more common term in North America, where autumnis nonetheless preferred in scientific and often in literary contexts.
Association with the transition from warm to cold weather, and its related status as the season of the primary harvest, has dominated its themes and popular images. In Western cultures, personifications of autumn are usually pretty, well-fed females adorned with fruits, vegetables and grains that ripen at this time. Most ancient cultures featured autumnal celebrations of the harvest, often the most important on their calendars. Still extant echoes of these celebrations are found in the mid-autumn Thanksgiving holiday of the United States, and the Jewish Sukkot holiday with its roots as a full moon harvest festival of â€œtabernaclesâ€ (huts wherein the harvest was processed and which later gained religious significance). There are also the many North American Indian festivals tied to harvest of autumnally ripe foods gathered in the wild, the Chinese Mid-Autumn or Moon festival, and many others. The predominant mood of these autumnal celebrations is a gladness for the fruits of the earth mixed with a certain melancholy linked to the imminent arrival of harsh weather.
This view is presented in English poet John Keatsâ€™ poem To Autumn, where he describes the season as a time of bounteous fecundity, a time of â€˜mellow fruitfulnessâ€™.