This favourite terminology from the BBC usually implies (I think) reduced
direct sunshine due to cirrus or other thin high cloud.

I wonder why they persist in using this misleading expression? Hazy
normally would mean reduced surface visibility due to dust or other
particles.

I realise that the BBC is talking to the general public who no doubt
understand perfectly well what is meant. But I am confused when they
sometimes refer to "Hazy Sunshine" and don't mean cirrus, but to genuinely
reduced visibility.

A new form of words is needed to describe reduced insolation resulting from
thin high cloud. Any suggestions?

Incidentally, on my gliding site, I use the term "thin top cover" to imply
that reduced sun will affect thermals, but this is hardly appropriate
terminology for Joe Public

Jack