What are 'fire clouds' that are worsening wildfires in Europe?

Recent wildfires in Europe have generated pyrocumulonimbus (fire clouds), which form when intense heat drives smoke and moisture high into atmosphere. The towering clouds can produce lightning, downdrafts and sudden wind shifts. These conditions fan flames, alter fire's direction and ignite new blazes. A wildfire in Saumos generated what reports described as France's first recorded fire cloud.