Spectacular photos of Yosemite's 'firefall' optical illusion

By: Emily Drooby, Buzz60

It's not hot lava, it's an optical illusion!

Every February, Horsetail Fall in Yosemite National Park lights up as if it were on fire.

See more: Lighting up Yosemite:

Many people flock to the falls hoping to catch a glimpse of the the phenomenal sight that only appears for 20 days around sunset in February.

It's an incredible illusion that can only happen under perfect circumstances; clear skies, enough rain and sun rays that hit the water just right.

Onlookers this year got a special treat! A National Parks Service Spokesman told CNN that, "the waterfall is bigger than it has been in a long time due to all the rain and snow we have received,"

Want to check out the firefalls? The park suggests heading to the El Capitan picnic area because the waterfall is visible from the road.

If you're lucky enough to see it in person make sure you have your camera ready, because the illusion only lasts about 10 minutes and you wouldn't want to miss such a great Instagram opportunity!