Astronomical winter arrives in Thornton today and with the solstice also comes the shortest day of the year.

Winter officially begins at 4:03pm today.  The Winter Solstice occurs when the North Pole is tilted at its furthest from the sun – 23.5 degrees away.  This results in the shortest day of the year in the Northern Hemisphere.

Here in Denver, with sunrise at 7:18am and sunset at 4:39pm, our day today is 9 hours, 21 minutes and 13 seconds long.  Tomorrow it will be one second longer and each day from now through to the Summer Solstice in June will get gradually longer as well.

Did you know that there is a difference between the astronomical seasons that we are discussing here and meteorological seasons?

Meteorological seasons differ slightly and are geared toward matching the calendar with the annual temperature cycle.  This is done primarily for meteorological observing and forecasting and in many ways it is more logical than the astronomical seasons.

For the Northern Hemisphere, the meteorological spring covers the months of March, April and May.  Summer brings the hottest months of the year and so meteorological summer is June, July and August.  Meteorological fall then is September, October and November followed by the coldest months of December, January and February as meteorological winter.