How is winter solstice related to the season of winter?

Question

Ok, December 22nd is the shortest day of the year in the northern hemisphere. Wouldn't it make sense for winter solstice to mark the dead of winter, which seems to occur sometime in February? Winter proper has just begun. Don't the seasons depend on how much sunlight is reaching the earth?

Answer 1

I think this is the fact you need in order to make sense of things:

There is a "lag of the seasons," meaning that the coldest time of year does not occur when the days are shortest and the sun is lowest in the sky. And the reason is clear once you think about it.

Yes, the shortest day is also the day when the northern hemisphere receives the least thermal energy from the sun. And the heat it receives as incoming solar energy (or "insolation") is much less than the amount of money that is lost by the earth as it radiates heat into space. So the shortest day of the year is the day when the northern hemisphere is COOLING AT ITS FASTEST RATE. But it continues to cool for approximately six weeks before the sun starts providing more energy each day than the earth loses each day (by radiating heat into space). When that happens, we are in the "dead of winter" and the earth will start becoming warmer, even though spring has not yet arrived.

It might make more sense to identify the three coldest months of the year (perhaps from December 6 to March 6) and call that winter. But the exact dates for those three coldest months will vary by location. So for simplicity (I guess) we just use the period from the winter solstice to the spring equinox and call that winter.

The above reasoning also applies to the "lag of the seasons" in the summer, where the hottest days occur in late July or early August. The earth continues heating up after the summer solstice, until it gets to the point where the amount of heat radiated to space each day becomes as large as (and then exceeds) the amount of heat (insolation) received from the sun each day.

Answer 2

John,

You make a logical point, but much of what relates to calendars is by tradition and not logic. In fact, the names of the "seasons" could be picked arbitrarily and begin at any time that the calendar makers chose. We have had a few modifications to the canendar over time to keep things in line with tradition. As an example or a traditional season, consider the Christian Lenten season. It begins 40 days before the first full moon before or after the vernal equinox in the Northern Hemisphere or the Autumnal Equinox in the Southern. Whew!! I think that I said that correctly.

The solstices as well as the equinoxes relate to specific relations of the Sun and Earth and as such, the dates and times of day of the occurances vary a bit.

For the "winter" soldtice in the Northern Hemisphere, that occurs when the direct rays of the sun fall at the highest latitude in the South (a tropic). That occurs at local noon in the Southern Hemisphere. Note that this is the older "local" noon as determined by the sun and not standard time.

There is a bit of physical reason for the choice of the beginnings of the seasons. Because the air and land of the Earth must catch up with the sunshine, there is a bit of inertia in warming up or cooling down. However, I think that the best answer for picking the names of the seasons and the times of beginnings is tradition.

Answer 3

Winter solstice, the shortest day of the year, is the day that the sun is directly over the Tropic of Capricorn, in the southern hemisphere. From now on the days get longer.
Weather seems to follow a 2 month lag as far as coldness or in the summer, the warmest time is in August, 2 months after the longest day.

Answer 4

Pagans and some indigenous societies celebrated both the beginning of the season and the middle of the season. December 21/22 marks the start of winter and the start of the return of light. February 2nd is called Candlemass or Imbolc and it celebrates the start of small hopes and new growth that will grow as the sun grows.

Answer 5

I live in Washington, DC, and it seems that we get the coldest weather from mid-January to mid-February. It makes sense to me, intuitively, that the coldest day of the year would follow, not happen *on*, the shorest day fo the year, since the ground and water probably take a while to cool off in the fall, and once cold it takes many days of warm weather and sunshine to heat them up. The air cools and warms quickly, but is influenced by the ground and water as well as the air.

Answer 6

your reasoning is obscure from astronomy facts and geophysical of the earth........plus the politics of daylight savings time...BUT winter solstice is the "beginning of winter" a geophysics fact..wherein, the dead of winter may be a lot different in Montana than AZ.