Winter solstice: Why the longest night in winter isn't also the coldest

While it may not seem even close to being winter in many parts of Canada, time does march on and it officially arrives today, on December 21, when we hit the Solstice. But what exactly astronomically and culturally speaking are we marking on this date in the year?

The December solstice is when the Sun hits the lowest point in the sky across the entire Northern Hemisphere and it occurs this year at exactly 11:48 p.m. EST on Monday, December 21. This astronomical event marks the beginning of winter for those living above the equator. Conversely, summer is beginning in the Southern Hemisphere.

Signaling a New Season

While Earth orbits the Sun it spins around its own axis, which is tilted on its side by 23.5 degrees. It is this tilt which gives us our four seasons. The Northern Hemisphere of Earth experiences summer when the North Pole is tilted toward the Sun. At the same time the South Pole is pointed away from the Sun and so the Southern Hemisphere experiences winter. The end result for us Earth dwellers is that the sun travels its lowest path across our skies, offering the shortest hours of daylight and colder weather.

In fact it’s because the Sun’s rays strike Earth at a steep angle that causes wintery temperatures to settle in across Canada and the entire hemisphere.

During summer solstice around June 21, the opposite happens and Earth’s North Pole is tipped directly towards the Sun and so it appears to trek higher in the sky and is visible for more hours a day, leading to warmer weather.

But if the solstice brings the shortest days and longest nights, shouldn’t it coincide with the coldest time of the year?

“Actually the coldest time of the year is delayed behind the astronomical season because it takes a while for the Earth's land and especially oceans to cool off. What this means for mid-latitude continental climates [like in southern Canada], the coldest time of year on average is in mid-January,” explained Mark Hammergren, astronomer at the Adler Planetarium in Chicago.

“This delay is referred to as the "seasonal lag", and ranges anywhere from a few weeks to more than two months depending on the local environment and climate.”

The world's oldest holiday

The word solstice has its roots in Latin, meaning “Sun stands still,” which it appears to do in our skies on December 21 before resuming its travels back northwards. But celebrating this celestial moment goes back to ancient times, where for many cultures the solstice was thought of as an auspicious occasion. And because there appears to be so many known rituals around the world tied in with the solstice, some scholars believe it may be one of the oldest holidays around.

For example, mysterious monuments such as the Newgrange tomb in Ireland was built such that it would be aligned with the morning sun around the Winter Solstice so that the sunlight would illuminate its interior passage and chamber.

Germanic peoples would have Yule festivals around the winter solstice, while ancient Romans had weeklong celebrations with food and games known as the time of Saturnalia.

Across the northern hemisphere, following the winter solstice, the Sun appears to rise higher and higher again each day, bringing with it a return of longer days and a promise of warmer temperatures. Ancient cultures often viewed the winter solstice as a very important holiday; one which Hammergren says “signifies reversal, rebirth and renewal.” But it also meant for many ancient tribes that it was time to begin hunkering down for the deepest and most grueling part of the season.

“Because of the seasonal lag, the winter solstice marks the beginning of the coldest depths of winter, frequently a time of famine,” said Hammergren.

“Animals were slaughtered to avoid having to feed them through the winter, which meant that the winter solstice was often celebrated with a great feast.”

Even today in our modern times the solstice has a deep connection with the Christmas holidays too that dates back to the religion’s earliest days. The traditional observances seen in Christianity mixed readily with the pattern of life, death and rebirth celebrated by winter solstice worshipers.

“With its similar theme and the popularity and widespread nature of the winter solstice holiday, it's not surprising that this time of year and some of its associated celebrations were adopted and naturalized by Christians,” said Hammergren.

“All we have to do is look at some of its classic traditions, like Christmas trees, wreaths, and Yule logs, [to see that they] are directly borrowed from pagan Scandinavian and Germanic practices.”