Spring equinox

Spring is here in the valley.

Today is the vernal equinox – the spring equinox – when the length of day and night are equal (equi = equal, nox = night). Actually, “They are not exactly equal, … due to the angular size of the Sun, atmospheric refraction, and the rapidly changing duration of the length of day that occurs at most latitudes around the equinoxes” [Wikipedia]. Here in New Hampshire, Sunrise was at 6:51am, Sunset at 7:01pm.

For those who welcome the arrival of spring, today is when we are adding more minutes of sun per day than at any other time. We’re on the steep part of the curve! This is great news for our solar tracker, which put in a banner effort today under nearly clear skies, with a total production of 45.57kWh:

Technically, the equinox is “the instant of time when the plane of Earth’s equator passes through the geometric center of the Sun’s disk” [Wikipedia]. This year, that occurred at 0937 UTC, or 5:37am here in Lyme, which happens to be about when I got up this morning.

Interestingly, it has long been noted this is the “day when the Sun rises due east and sets due west, and indeed this happens on the day closest to the astronomically defined event.” [Wikipedia again].

On cue, the Connecticut River decided it is also ice-out day – the day the winter’s ice breaks up and the river begins to visibly flow. I’m pleased to see open water, because it means that bald eagle might be seen more often in our neighborhood once again, now that it has an opportunity to fish.

ice-out on the Connecticut River, in front of our house

The forecast shows nothing but clear skies, warm days (50-60º) and cool nights (20-30º). Great weather for sugaring! More on that to come…

Author: dfkotz

David Kotz is an outdoor enthusiast, traveller, husband, and father of three. He is also a Professor of Computer Science at Dartmouth College.

One thought on “Spring equinox”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s