What is a 'nuee ardente'?

A 'nuee ardente' refers to a superheated cloud of gas and volcanic ash that flows down the slope of a volcano. This phenomenon occurs during certain explosive volcanic eruptions, where the mixture of gases, ash, and pyroclastic material can move rapidly and at high temperatures. The term originates from French, meaning “glowing cloud,” and describes a highly dangerous natural disaster that can travel at speeds of hundreds of kilometers per hour, engulfing everything in its path. Understanding this concept is vital, especially in the context of the eruptions that affected Pompeii and Herculaneum, as these cities were ultimately buried under pyroclastic flows generated by the eruption of Mount Vesuvius.