Getting More Than Enough Sunlight

Robert Turner in Bowling Green, Kentucky, writes:

Our home sits on a steep bluff overlooking a river, about 60 feet above water level and laterally about the same distance from the river’s edge. The house is oriented south, and during the winter months, we get direct sunlight and solar heat gain through the numerous windows that overlook the river. There seems to be a doubling effect of this heat gain by virtue of the reflection of sunlight from the surface of the water bouncing up to those same windows. Is that possible?

Yes, you’re getting way more sun (the amount depends on many factors) from the rays that are redirected from the river. Water skiers are painfully familiar with the phenomenon. They must apply enough sunblock to overcome: a) the direct exposure (from above) to the UV rays; b) the indirect exposure (from the water); and c) the water washing off their sunblock.