Horsetail Fall is a seasonal waterfall that only flows in late winter and early spring. For a few days every February, the water turns an igneous orange for a few minutes at sundown.
WATCH: Yosemite firefall: Horsetail Fall brilliantly illuminated as sun sets at specific angle in Yosemite Nat'l Park. pic.twitter.com/6tcfHWJTq6— NBC Nightly News (@NBCNightlyNews) February 15, 2017
“[The firefall is] this thin ribbon of water just glowing orange with the cliff and the shade behind it, so it just seems like it has its own source of light — that there’s nothing else creating it. It’s really an amazing and beautiful thing to see,” photographer Michael Frye told the National Park Service.
According to Yosemite, very specific conditions lead to the firefall. Horsetail Fall must be flowing, meaning there can’t be too much snow packed into it. Secondly, the sky must be clear so clouds won’t block the sun’s rays.
This year’s firefall was particularly brilliant. "Last year you couldn't see the fall without a camera lens. This year, from where we're at, you can see the top of the waterfall,” said firefall enthusiast Tom Neumayer.
"The waterfall is bigger than it has been in a long time due to all the rain and snow we have received," said National Park Ranger Scott Gediman.
"It has gained popularity the last few years due to social media. People come from all over the world to see this.”
The phenomenon, discovered in 1973, draws hundreds of visitors hoping to catch sight of the fluorescent orange water. "This year, I feel fortunate to have been one of the firsts to witness it," wrote amateur photographer Sangeeta Day in an instagram post. "In fact, I just drove back home after seeing this unforgettable moment."