Drips

It's condensation. Heating the roof would stop it. Applying an insulating layer of foam, cork, or rubber might stop it. Spraying it with anti-fogging oil or rubbing it down with soap or wax might help a little. Tilting the roof enough so that the condensation can run along the low points to drip off in a less objectionable place would probably work, but generally I'd say just live with it. Stuff that's outside needs to be able to take a little water.

--Goedjn

But to OP note if it's not a direct application there's at least a reasonable likelihood in a totally unheated area of simply having condesation above the insulation which is potentially worse in the long run than the present problem -- at least now it will dry up when the weather warms up/dries out.