You may have observed recently that our city streets have started turning wet and slushy during even the coldest of days.
If you have parked your car in the sun, you may have noticed the car's interior is noticeably warmer than it was in similar conditions a few weeks ago.
The difference is in solar radiation. It has been seven weeks since the winter solstice. Even on a cloudy day, the sun's rays are reaching the ground at a much higher angle and striking the ground much more directly.
The sun is roughly as high in the sky now as it was around Halloween last October. When the sun goes down at night, this radiational warming is lost, and the streets become icy again. Not only can this make for slippery roads, but it is also the principle cause of potholes in the streets.