Reflection off the Atmosphere
Since the Sun is below the horizon, there is no direct path for the light to reach the mountain. Instead, light reflects off airborne snow, water, or ice particles low in the atmosphere. It is this circumstance that separates a normal sunrise or sunset from alpenglow.
Wedge Pond is perfect for this natural phenomena. Last year I took a similar shot but had to doctor it up a bit. This year, armed with split neutral density filters, there is not reason to manipulate the image to get what is real. I also included a little foreground to break up the reflection. Not sure if it was right or not.