Yosemite waterfall appears to be 'on fire' due to ... the right position in the sky so that five to 15 minutes before sunset, the Sun's rays pass directly through the waterfall.

YOSEMITE NATIONAL PARK ... like visual is only seen when the conditions are perfect, and the sunset aligns with the waterfall just right. Even with perfect conditions and clear skies, Firefall ...

The annual Horsetail Fall event at Yosemite ... iconic waterfall glow like an erupting volcano. "On rare occasions during mid-to-late February, it can glow orange when it's backlit by sunset ...