Facing the sun

As a soaring pilot you know how important it is to identify thermal sources and triggers.  Early or late in the day the sun is at a low angle and the difference in heating can be quite substantial from a surface angled towards the sun or away.

I was checking some ceiling temperatures, to test insulation in the new roof, with an infrared thermometer and looked out onto my roof and wondered what the temperature difference would be.

The first picture is the South side of the roof.  Angled nearly straight at the sun at high noon in December.  The second is the North side of the roof.  Angled maybe 40 degrees away from the sun.  The difference is nearly 60 degrees.

Think about that the next time it is late in the day and you're trying to find something to get yourself home.