Acrylic and pastel paintings.
These are "chemtrails" ( popular vernacular) other name: aerosol spray used in geoengineering to modify earth's weather patterns. main ingredient is aluminum particulate along with barium, strontium and nano-polymers. Easily researched on the internet or go to "geoengineering.org" dane wiggington et al
There are thousands of these "jet trail" photos on the chemtrail internet sites. Look at manitoba skywatch, or skyder alert. People all over the globe are trying to point out that this aerosol assault is happening to those who don't look at the sky. All European countries have these sites. They are all as upset about the spraying as are we North Americans.