METEOROLOGIST JEFF HABY
Around September 23rd is the autumnal equinox. This is the day every point on the earth will have 12 hours of daylight
and 12 hours of darkness (finally some solar fairness with respect to day length),
It is a misconception that on the equinox
the earth is not tilted on its axis. On all days of the year the earth is tilted by 23.5 degrees from the vertical. This
tilt causes the seasons.
On the equinox, the earth's tilt is perfectly perpendicular to the sun's radiation, thus from the sun's perspective
the earth is tilted neither toward or away from the sun. At the equator, the sun will be directly overhead at solar noon
on the equinox. Shadows will be cast straight down at the equator at solar noon. If you put a 100% chance for an equinox
in your forecast on September 23rd (or very near this date depending on year), your forecast will be guaranteed
to verify (as you can see astronomical predictions are often easier than weather predictions).