Yesterday was the winter solstice, with winter officially arriving at 5:23pm ET. Now that today is the first full day of winter, the days will begin to get longer in the Northern Hemisphere. Thanks to the tilt of the Earth’s axis, yesterday’s solstice is either the longest or shortest day of the year. In the Northern Hemisphere, “peak” sunlight usually occurs on June 20, 21, or 22 of any given year at the summer solstice. In the Southern Hemisphere, peak sunlight arrives today, while the opposite happens here in the Northern Hemisphere. Beyond today, the days will begin to get longer until Summer Solstice arrives. The change in seasons is completely based on the tilt of the Earth and has nothing to do with the distance to the sun. In just a few weeks in 2019, the Earth will be the closest to the sun on January 3.
The word “winter” comes from the Germanic wintar which in turn is derived from the root wed meaning ‘wet’ or water’, and so signifying a wet season. In Anglo-Saxon cultures, years were counted by the winters, so a person could be said to be “2 winters old”.
While the calendar says winter is officially here, meteorologists unofficially count December 1 as the start of the winter season. And even though winter just started and the days are getting longer, the colder days of the season are ahead. Even though daylight slowly starts to increase after the solstice in the Northern Hemisphere, the coldest days of winter in many parts of the United States – and other countries north of the equator – are usually not until January. This is because the amount of solar energy arriving at the ground is less than the amount leaving the Earth for a few more weeks. Oceans and bodies of water, which take longer than land to heat up and cool down, keep temperatures from rising very fast. Not until the Northern Hemisphere sees a net gain in incoming solar energy do temperatures begin their slow upward climb. And such a climb will occur as Spring approaches.