Cinematic 4K. Cirrus is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word cirrus meaning a ringlet or curling lock of hair. Timelapse forest mountain hill woods trees pine forests blue dark sky white green spring summer autumn morning nature natural afternoon wind slope dome mount deep valley ringlet curling thin temperate regions deposition tropical cyclones weather conditions ice crystals jet stream main cloud layer cirrostratus cirrocumulus cloud tufts pattern Green pine forest. Time lapse air. 3840×2160 4K UHD.