GOES Visible Channel - asymmetry between morning and afternoon In the GOES-13 Visible channel, there seems to be a morning/afternoon asymmetry in the data. I'm wondering what might cause this. 

In this example data, the morning is the lower branch, and the afternoon is the upper branch. The y-axis is the pixel level (0..255), the x-axis is the Sun's local altitude above the horizon. The location is the Gulf of St. Lawrence, on the east coast of Canada. 

Latitude +46.94N, longitude -63.21W (not far from the center of the images below.)



Morning, 10am local time:


Afternoon, 4pm local time:
The absolute accuracy for GOES-13 visible channel is 5%, so 2% is well within the noise. http://noaasis.noaa.gov/NOAASIS/ml/imager.html