Days are getting longer, but winter is still young
Published 7:00 am Tuesday, December 27, 2016
Have you noticed that the days are getting longer? Not the 24-hour day, of course, but the duration of daylight is now getting a little longer each day.
Ever since the summer solstice last June 20th, the amount of daylight time decreased each day for those of us in the Northern Hemisphere. You may have missed it, but last Wednesday, December 21st, the day’s duration reached its minimum for the year.
Here at our latitude in Mississippi that amounted to 10 hours and 11 minutes of daylight. Compare that to only 3 hours and 43 minutes for our fellow Americans much farther north in Fairbanks, Alaska.
Everywhere in the Northern Hemisphere, including Fairbanks and Picayune, the daylight time has been increasing since last Wednesday, and will continue to do so until the next summer solstice in June.
At our latitude the increase in daylight is quite small from day to day, ranging from less than a one minute increase per day this week to a little more than two minutes per day in March.
This week’s increase in Picayune is comparable to the increases much further north. But by the time we get to March the increase in daylight in Fairbanks will be averaging over seven minutes per day.
Given the amount of darkness they have to deal with each winter, who can begrudge them a faster increase as spring approaches.
Even though our days are getting longer, on average in the
Northern Hemisphere the amount of energy being lost each day will still be greater than the amount we are receiving from the sun for the next couple of months. That’s why the winter solstice is often called the first day of winter.
The average high and low temperatures for Picayune for the last week in December are 62 and 38 degrees respectively.
Those averages are nearly the same for the entire winter month of January before they slowly begin to climb in February.
Typical winter temperatures, however, have been hard to find in south Mississippi over the last week.
If current forecasts come true, tomorrow will be our sixth straight day with high temperatures in the 70s.
This is the second straight year when more air conditioners than heaters were in use on Christmas Day in south Mississippi.
A major reason for our warm weather has been that the upper jet stream has stayed far to the north over the past week. But, this Thursday the jet stream will once again dip southward over the eastern one-third of the U.S.
Associated with the jet stream’s southward dip, a surface cold front will move through the Gulf South.
Behind the front, Friday will be our coolest day since early last week.
Over the weekend, according to the computer weather models, low pressure will form in the Gulf and Thursday’s cold front will head back north as a warm front along with a large shield of rain.
Depending on the timing of the system, it could put a damper on New Year’s Eve and/or New Year’s Day activities.
By Skip Rigney