JANESVILLE, Calif. -- A surreal sight greeted firefighters as they battled the massive Dixie Fire in northern California last month: A "firenado".
The footage was captured by firefighter Casey Zenger on Aug. 16 near Janesville. He says he took the video as his team's fire engine was trying to protect a home from the encroaching flames.
Zenger says they saved the house.
These whirls of fire are caused when the rising air from the wildfire’s intense heat creates a column of flames that rise towards the sky.
They typically are 33-100 feet tall and have inside wind speeds of about 20-60 mph. The smallest whirls can be just a couple feet across while the largest can span 500 feet in diameter.
NOAA researchers say the most favorable condition for fire whirlwinds are over a hot fire near the top of a steep slope with strong winds over the ridge top.
The Dixie Fire has now burned nearly 850,000 acres in the 48 days it's been burning, ranking as the second-largest fire in the state's history, according to Cal Fire. Fire officials report the fire is 52% contained.