The setting sun transforms Horsetail Fall into a firefall in Yosemite National Park. (Getty Images/Haoxiang Yang/500px) Two weather factors need to come together perfectly for the firefall to ignite.

It may look like lava gushing from Horsetail Fall at Yosemite National Park. But that's just an illusion. In reality, this phenomenon, known as "firefall," happens when the sun's angle "sets the ...

Photos from a Firefall occurrence on Feb. 5 show how realistic the fiery appearance of the waterfall is. Hundreds of people flock to the eastern ridge of the El Capitan in Yosemite National Park ...