"in a plot with the witches who let the winds out of their knotted handkerchiefs up towards the Finnish border"

The 'witch's knot' has been a staple in folklore for centuries; it was believed that it acted as a charm to ensure a spell or chant would hold its power.  It has also been a longheld superstition to tie a knot in one's handkerchief for good luck.  Witch's knots are most associated, however, with using magic to control the weather.  Storms could be raised or calm restored depending on the intentions of the witch - and the knot could be tied in cords, or even her own hair.  The term 'witch's knot' is also used to describe the knotting in a horse's tail or mane, and comes from the same old belief.  Throughout parts of Europe, including Finland, sailors believed that the wind could be controlled by the tying and untying of knots, and would purchase knotted handkerchiefs from people who specialised in offering them for sale; it was understood that the knots were tied by witches, both male and female.  In Great Britain, this belief was widespread throughout Cornwall, Shetland, Lewis and the Isle of Man.