What Is The Morning Dip? Why Do Temperatures Get Colder Right After Sunrise?
Living in the Northland for any length of time you start to pick up on accepted weather-related norms: things like "colder by the lake" and "it usually doesn't snow when it's cold". Usually these accepted facts have a variety of science (and sometimes geography) to back them up.
One of those factoids that gets thrown around a lot is the "morning dip" - the observance that temperatures usually dip just after sunrise. While that dip occurs during all seasons, it seems to be noticed the most in the winter when a cold overnight suddenly gets even more brutal after the sun comes up.
The observation isn't without science to back it up. I found a good explanation of the phenomenon from two professors in the Department of Atmospheric and Oceanic Sciences at UW-Madison - that run a weather-related website. To summarize the science, the Earth has infrared energy that solar energy from the sun counter-balances. In the time frame that happens right after the sun comes up there isn't enough solar energy to burn off the infrared energy.