Today we officially bid farewell to summer and welcome the new season of Fall. The Autumn Equinox is at 2:50 am this Saturday. The word “equinox” means “equal night”. Every point on Earth gets approximately equal day and night today. The length of day isn’t exactly 12 hours. It’s 12 hours and 8 minutes. There are two reasons why we get an extra 8 minutes.
First, we don’t measure sunrise and sunset from the middle of the sun. Sunrise is when the first top tip of the sun appears over a totally flat horizon and sunset is when the last tip of the sun disappears below the horizon. Second, sunlight bends ever so slightly as it enters the Earth’s atmosphere, giving us an extra couple minutes of daylight.
This pic. is from the webcam at the South Pole – I grabbed this back in 2020. This was the weather at the South Pole early this AM (2023).
Lovely fall day, eh? Here at the South Pole, the top tip of the sun will appear today, after six months of staying below the horizon. In the Southern Hemisphere, the Equinox in September is the start of the spring season.
The building above is the Amundsen-Scott South Pole Station, dedicated in January 2008,. It starts summer operations in October of each year. The station typically remains in summer operating mode until early February, at which point the eight-month long winter season begins.
At an elevation of 2,835 meters (9,300 feet), the South Pole has an average monthly temperature in the summer of -28°C (-18°F); in the winter, the average monthly temperature is -60°C (-76°F). The warmest temperature ever at the South Pole was +9.9F on 12/25/2011 and the coldest was -117.0F on 6/23/1982. The coldest ever in Antarctica was -128.6F on 7/21/1983, though a satellite measured a ground temperature of -135.8F.
By contrast, it’ll be a relatively warm day over much of the U.S., with many high temperatures in the 70’s and 80s.