Dust storms are a normal, annual condition on Mars, often covering nearly the whole planet. Nothing new or strange about it.
The Telltale consists of a gallows that is mounted on the top of the Meteorological Mast of the Lander. The active element of the instrument is an extremely lightweight Kapton tube hanging in Kevlar fibres. Images taken of the instrument will show the deflection of the Telltale due to the wind. A mirror is mounted below the active part to enable better direction information.
