This Natural Phenomenon Makes Water Look Like Flowing Lava? Each February, Yosemite’s Horsetail Fall transforms into a natural spectacle known as the “firefall,” when the setting sun hits the seasonal waterfall at just the right angle to make it glow like molten lava. This fiery illusion is not due to any geological anomaly, but a perfect alignment of physics and timing. For a few fleeting minutes, the sun’s low-angle rays pass through the western horizon and strike the waterfall, which must als