The buoyant plasma hypothesis proposes that ball lightning is a bubble of hot, ionized gas (plasma) that maintains its luminosity and cohesion through a balance of internal pressure, buoyancy, and electromagnetic self-confinement. In this model, a lightning strike heats a localized volume of air to extreme temperatures, creating a bubble of plasma less dense than the surrounding atmosphere. Like a hot air balloon, this bubble rises and drifts, glowing as the ionized gas emits light.
The bubble's cohesion is maintained by electromagnetic forces — the charged particles within the plasma create magnetic fields that resist dispersion. The model predicts that ball lightning should slowly rise and drift with air currents, which is broadly consistent with many observations. It also explains the typical duration (the plasma cools and the bubble dissipates over seconds to minutes) and the occasional explosive disappearance (if the bubble ruptures suddenly, the rapid mixing of hot plasma with cool air could produce a shock wave). Critics note that simple plasma bubbles should cool and dissipate much more quickly than the observed duration of ball lightning, suggesting that an additional energy source or confinement mechanism must be at work.