The Dragon Bravo wildfire has been burning for over a month, and U.S. firefighting agencies are too understaffed to stop it.

Pyrocumulus clouds, otherwise known as flammagenitus or “fire clouds,” develop due to “convection initiated by heat from forest fires, wildfires or volcanic eruption activity,” according to the World Meteorological Organization.

According to the fire tracking app WatchDuty, as of Monday, the fire had burned through over 120,000 acres. However, the blaze is only 16% contained, as dry vegetation and low humidity have made fighting it increasingly difficult.