The Winter Solstice arrives December 21 at 10:03 AM Eastern Time. At this moment, the sun is the farthest south in the Northern Hemisphere.
This is also when astronomical winter begins as opposed to meteorological winter, which began December 1st. The days get longer during winter, but it isn't so noticeable at first. As the Spring Equinox approaches, the longer days are more noticeable.
Since the days get longer during winter, and therefore have increasing amounts of sunlight, why do the coldest temperatures happen then?
AFN spoke with Climatologist David Legates of the Cornwall Alliance.
"Think about your thermostat. So, if you went to your thermostat, and let's say it's set at 70°, and you turn it down to 50° for 10 minutes, your air conditioner will kick in. The temperature will start to lower. But chances are you don't have that powerful an air conditioner that can lower the temperature that fast. It's going to take a while to drop the temperature, and the same thing happens at the Earth."
He said even though the sun's energy input is lowest on Dec 21st the earth still has some heat from the previous summer and even fall.
The temperature continues to drop even though the sun's incoming energy is increasing.
"By the time we get to mid-February, the temperature drops low enough, the incoming solar radiation has risen enough that we start to turn back over. We start to warm the Earth's surface and therefore the northern hemisphere starts to warm. It's late January, early February before the coldest temperatures occur, even though the shortest day actually occurs on December 21st."
