FYI, those aren't nuns. Those are Breton peasant women wearing the traditional costume. The elaborately crimped and trimmed starched hats are typical of French, Swiss, and some German traditional costumes.
Ooops. I guess that Sally Field image just won't get out of my head, flying around in that early TV series.
You are absolutely right about the nuns; thanks for a great picture of their traditional costumes.