A long time ago, and far away, in a different and better life, there was snow*, and I used it to dye fabric.
Fiber-reactive dye is poured on snow piled atop scrunched-up fabric. As the snow melts, the dye comes in contact with the fabric; different rates of melting and different concentrations of dye create patterns.
I still haven't used these fabrics. I should.
* Last Saturday it was so warm I sat Outside in a tailgate chair to drink a beer. Sigh.