Check out the US waterfall that's 'on fire'

A spectacular, natural phenomenon is getting ready to light up the evening sky at a national park in the US state of California.

Known as the "Yosemite Firefall," it sees one of the park's waterfalls, called Horsetail Fall, glow bright orange - it looks a bit like lava spilling down a volcano.

But don't worry, it's not actually molten rock!

The glowing effect is created when light from the setting sun hits the waterfall at just the right angle.

Keep reading to find out more about the firefall, and why it only occurs in February.

The special spectacle happens every February, in California's famous Yosemite National Park.

It happens for a few minutes at sunset, as the waterfall called Horsetail Fall, runs down the side of a big rock formation known as El Capitan, and appears to glow like it's on fire - a phenomenon that's call the "Firefall".

It's all down to a natural trick of light and water, that takes place just before the sun dips below the horizon.

As the sun sets, Horsetail Fall and the wall behind it are hit by the setting sun.

The sunlight streams through the falling water, turning it into a cascade of fiery colour.

The firefall attracts thousands of visitors every year, from around the second week of February, all hoping to catch a glimpse of the event.

However, the weather in the National Park this week has been cloudy, and the water flow's been weak, meaning that the crowds of people are still waiting to see the phenomenon properly take place.

Three different factors are needed to line up at the exact same moment, in order for the magic to work - and this only occurs around a two-week window this month.

First of all, the sunlight has to hit the waterfall at the right angle, which only happens in mid-to-late February each year.

There also needs to be enough water. Horsetail Fall is a seasonal waterfall that mainly flows during winter and early spring, fed by melting snow and rainfall.

And finally, clear skies are needed for the Firefall to occur. Even a small amount of cloud at the wrong moment can block the sun and prevent the whole effect from taking place.