The Horsetail Fall in Yosemite National Park transforms into a "firefall" every year from mid-to-late February (Credit: Jay Huang Photography/CC-BY-SA 2.0 /Flickr)

California's Yosemite National Park is home to numerous stunning waterfalls. However, from mid-to-late February each year, the unlikely star of the pristine preserve is Horsetail Fall — a small, nondescript waterfall that forms over the eastern edge of the park's famous vertical rock formation, El Capitan, every winter. That's because, during the two-week-period, the temporary 1,000-foot fall frequently transforms into a spectacular "firefall" for about ten minutes a day during sunset.

For the phenomenon to occur, several conditions need to coincide. There must be enough snow and the temperatures have to be warm enough for it to melt and form the waterfall. During drought years, Horsetail Fall is reduced to a trickle or does not appear at all. Additionally, the skies have to be entirely clear. Even a slight haze is enough to ruin the illusion of fire tumbling down the cliffs. Finally, the sun has to strike the water from the right angle to "set the waterfall ablaze."

A number of conditions need to occur at the same time for the "firefall "to be visible (Credit: Kem Xu/ CC-BY-SA 2.0/Flickr)

The "firefall" has been popular with professional and amateur photographers since the 1940s. However, in recent years, thanks to social media, its fame has risen to new heights, with thousands of people flocking to the national park each February. In 2019, over 2,200 people crowded into the small viewing areas on February 22, the best day to see the light show last year. However, the visitors not only trampled over sensitive vegetation but also left behind large amounts of trash.

To prevent a repeat of the unfortunate incident, in 2020, the park service has closed two of the ideal viewing areas. The only one open requires a 1.5-mile-long hike. However, the 3-mile round-trip, as well as a warning by the officials that a dry spell has turned the fall into a trickle, leaving the possibility of a "firefall" in doubt, does not seem to have deterred fans. Hundreds of people have been making their way to Horsetail Fall to catch a glimpse of the light show, which will be visible from February 12 to February 28, 2020. The numbers are expected to peak once again on February 22, 2020, which, for the second consecutive year, will be the optimum day to watch the stunning spectacle. Hopefully, Horsetail Fall enthusiasts will be more respectful of the natural environment this time.

Resources: odditycentral.com,nps.gov, www.theguardian.com