Mirror image?

I was driving back from Cardigan in the late afternoon a few days ago when I noticed light rays on the horizon. 

 

This may not seem at all significant.  We often see this effect on days were there is broken cloud as the sun passes below the horizon. What made this event unusual was that this photograph is of the horizon to the east.  The light spot seen a little way above the horizon is the Moon which was being illuminated by the sun which was sinking behind me to the west.

As the bank of clouds in front of the light source were not being illuminated by the sun, the sun appeared to be too low to shine directly on the source of the light rays.  I suppose it is possible that the sun was just high enough to strike light source but all of the rest of the clouds in the foreground were in some way masked from the sun. The only other explanation I could think of is that the sunlight coming from behind me was being reflected off ice crystals in the upper atmosphere and striking a cloud on or below the opposite horizon which then acted like a bright light source.

 I am open to any other suggestions.