Figure A is the 10.7 micron image and Figure B is the 12 micron image, both from GOES-8 and both are valid at 1645 UTC.  The color tables are the same.  The images show that difference between the brightness temperatures is roughly 2 C.  The skin temperature field produced using Figure A and B is shown is Figure C.  The color table is different for the skin temperature product.  The visible image at 1645 UTC is shown in Figure D to more clearly identify the locations of clouds.  Of interest in this example is the temperature gradient that stretches from southern Indiana to the Panhandle of Texas.  Loop 1 displays 5 images of the skin temperature product, spanning 4 hours (1315 - 1715 UTC).  Plotted on each image are the surface winds (m/s) and the contours of station temperature.  The air temperature field seems reasonably represented by the skin temperature field, though they are not  necessarily equal.  During the morning to afternoon hours, the air next to the surface is warmed through conduction by the surface.  Thus, during the morning hours the air temperature will typically lag the skin temperature.  It is possible for advection to overcome the effects of conduction, but this front does not appear to have the advection required to do so.  Also notice that the ground in MN that was covered by clouds appears cooler than neighboring ground due to gradients in solar insulation.