in the clouds imaged
in Virginia by Ken Musgrave.
©Ken Musgrave ,
shown with permission.
The blurred bright shape on the cloud underside at left is a partial
map of the Potomac River. Ken Musgrave vowed that some day he would
capture a complete one.
Sunlight striking the river and landscape is scattered back upwards
to light the cloud. The water scatters and reflects more light. Its
multiply curved surface acts as mirror reflectors.
'Reflection' is a term reserved for light scattering from large surfaces
that are smooth compared to light's wavelength like polished metals
and liquid surfaces..
Eskimos were said to have used similar sky maps - ice blinks - produced
by sunlight scattered from ice floes and icefields.
Sometimes, in less frozen lands, fields of brightly coloured crops
can be located
by their light scattered onto low clouds.