Telltale

A small yarn or ribbon that indicates airflow over a sail.

How to sign

Use Dominant relaxed R-hand or 5-hand: yarn. The base or passive hand is Non-dominant flat-B: sail surface. Set the sail surface. Place the loose hand at one fixed point on it. Flutter the hand in a short, light irregular motion; add project WIND if airflow is the focus. Return to the same sail-surface point and release. At the established sail surface, use a loose R-hand or 5-hand to show a short yarn fluttering. Follow it with the lexical WIND sign if airflow is central.