Ice CAN accumulate in clear air. *It's usually Graupel but can be just
very light supercooled mist. *Neither block visibility enough to be
easily seen from a distance.

The kind of freezing rain described by the first poster is rare but
almost always fatal to an aircraft. *As a result there are few 1st
person stories of encounters with freezing rain.

Let me relate an iceing story that happened to me. I was on a cross
country in my PA 140 across the cascades. The weather was clear, the
winds calm. The temp was well below freezing. As I let down on the
west side of the mountains I encountered scattered clouds with light
showers. The temp. was well above freezing. After landing at
Longview I pulled up to the fuel pump to top off the tanks for the
return flight. To my surprise the fuel tanks were covered in ice.
The fuel had retained the cold temps enough to freeze the light rain
showers contacting the tank area. I felt no loss of lift as the rest
of the wing was clear. I wondered what the outcome might have been
with a large leading edge tank.

Ed