Researchers forecast longer, more extreme wildfire seasons

In California, a changing climate has made autumn feel more like summer, with hotter, drier weather that increases the risk of longer, more dangerous wildfire seasons, according to a new Stanford-led study.

Early sowing systems can boost Australian grain industry

New findings from research by La Trobe University and CSIRO made possible with GRDC investment could lead to a significant increase in the Australian wheat crop yield—adding potentially around $1.8 billion to the national ...

Winter solstice: The astronomy of Christmas

From the Neolithic to present times, the amount of sunlight we see in a day has had a profound impact on human culture. We are fast approaching the winter solstice for the Northern hemisphere, which takes place on December ...

Songbirds set long-distance migration record

Researchers at Lund University in Sweden have studied flight routes to determine how far willow warblers migrate in the autumn. The results show that the willow warbler holds a long-distance migration record in the ten-gram ...

Climate change could affect fall foliage timing

Climate change could substantially alter the timing of the autumn season in New England over the next century, a new study finds – in ways that are not simply based on rising temperatures.

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Autumn

Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September (Northern Hemisphere) or March (Southern 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. Some cultures regard the autumnal equinox as "mid-autumn", 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.

In North America, autumn is usually considered to start with the September equinox. In traditional East Asian solar term, autumn starts on or around 8 August and ends on about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October and November. However, according to the Irish Calendar which is based on ancient Celtic traditions, autumn lasts throughout the months of August, September, and October, or possibly a few days later, depending on tradition. In Australia, autumn officially begins on March 1st and ends May 31st According to United States unofficial tradition, autumn runs from the day after Labor Day (i.e. the Tuesday following the first Monday of September) through Thanksgiving (i.e. the fourth Thursday in November), after which the holiday season that demarcates the unofficial beginning of winter begins.

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