cyanometer postcards

These postcards were made for the 13th Architecture Venice Biennale, drawing on Horace-Bénédict de Saussure's cyanometer, a tool invented in 1789 for measuring the blue of the sky. Besides the blue, Ruiz-Tagle makes variations for grading shades of sunset and polluted skies. My pal @Abbey Nova sent me one to add to my collection (I have another cyanometer by Dust Collective); it's an excellent little gift for a sky-watching friend.