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WeatherWise: The Vernal Equinox

vernal equinox
Posted at 5:16 PM, Mar 20, 2023

Adios winter, hello spring! On this momentous occasion, the vernal equinox, the sun is positioned directly above the equator, something that happens twice a year: on this date and on the autumnal equinox in September.

Equinox means "equal night" in Latin. On the date of an equinox, daytime and nighttime have similar but not quite equal lengths. This has everything to do with the way the planet moves. Earth's axis is tilted at a 23.5-degree angle relative to the plane of its orbit around the sun.

And wasn't the first day of spring always march 21? From the year 1981 to 2102, Americans will celebrate the first day of spring no later than March 20. This is because the Earth's elliptical orbit changes its orientation relative to the sun.

The pull of gravity from other planets also affects the location of Earth in its orbit. Because of this spring averages 92.8 days, and Summer is the longest season at an average of 93.6 days. Winter is the shortest season at an average of 88.9 days long.

But now that the northern hemisphere tilts toward the sun that should mean longer, sunnier days… key word here is “should.”