Artistic Barometer — “Cyclist in a Puddle”
A decorative cobalt hygrometer postcard that indicates changes in atmospheric humidity by changing colour. The large crystal ball in the illustration acts as the humidity-sensitive element. Its colour changes gradually according to the moisture content of the air, from blue (dry) to pink (humid). The hygrometric coating contains cobalt salts, whose colour responds reversibly to changes in humidity. In drier air the ball becomes blue, while increasing humidity shifts the colour through violet towards pink. The postcard therefore works as a simple traditional chemical hygrometer, while also serving as an unusual decorative reproduction inspired by historical weather-indicating cards. The reverse side of the postcard is completely blank, leaving it suitable for a personal message, display, framing or collection. Size: 10 x 14 cm. Shipping note: If your order contains only one or more postcards, they will be sent by regular mail without tracking.