Blue lava

"Blue lava" is an electric-blue fire that burns when sulfur combusts, producing a neon-blue flame.

Sulfur burns when it comes into contact with hot air at temperatures above 360 °C (680 °F), which produces the energetic flames.

[4] Due to the blue color of the flames, the fires are essentially visible only at nighttime, as they are otherwise indistinguishable during the daytime.

[8] The blue fires also occur in Yellowstone National Park during wildfires, when fires burn and melt the large amounts of sulfur present in the park, creating the appearance of burning blue rivers of lava during such events.

Remnants of past episodes exist on the ground in the form of black lines, where fires have previously melted sulfur.