In the hustle and bustle of the holiday season, many might overlook the winter solstice. And in case you didn’t know, the winter solstice is tomorrow, December 21, 2018!
What exactly IS the Winter Solstice?
The winter solstice is the official start to astronomical winter and marks the shortest day, and the longest night of the year in the Northern Hemisphere. This is the exact moment that the Northern Hemisphere is most tilted away from the sun and usually falls on or around December 22 every year. In the Northern Hemisphere, this occurs when the noon sun shines directly over the Tropic of Capricorn (located 23.5 degrees north of the equator). This year that will occur at 5:23 PM EST.
That doesn’t sound fun. Does that mean that the sun will set at its earliest tomorrow?
Not at all! In fact, most locations in the mid-latitudes see their earliest sunset about two weeks before the solstice, while the latest sunrise is not until early January. So even though getting out of bed might be a little tougher in January, at least we’ll all still be sticking to our New Year’s resolutions to give us some motivation to wake up when it’s still dark.
Wait, let’s back up…I thought winter started already?
It did…for meteorologists and climatologists. We break the seasons down into groupings of three months based on the annual temperature cycle, as well as our calendar. Meteorological winter includes December, January,and February; meteorological spring includes March, April, and May; meteorological summer includes June, July, and August; and meteorological fall includes September, October, and November.
Why can’t meteorologists, climatologists, and astrologists just agree on seasons, and make it easier for all of us?
Earth’s rotation forms the basis for the astronomical calendar – the one that defines seasons based on equinoxes and solstices. Since the Earth actually makes a trip around the sun every 365.25 days, an extra day is needed every four years (which is why we have a Leap year!). This causes the exact date of the solstices and equinoxes to vary. Plus, the elliptical shape of the Earth’s orbit causes the length of astronomical seasons to vary between 89 and 93 days. These variations in season length and season start would make it difficult to consistently and accurately compare climatological statistics from year to year. Thus, the meteorological seasons were born!
Happy Winter Solstice! Hopefully, it isn’t too rainy where you are (sorry to folks living in the East, rain is in the forecast for us tomorrow!) so that you can get out and enjoy some natural light on the shortest day of the year!