This is an interactive, physically informed illustration of an electrified thunderstorm. It is not a numerical weather prediction or an electric-field solver.
Charge is separated by microphysics
Collisions involving ice crystals, riming graupel and supercooled droplets can transfer charge. Updrafts and different fall speeds separate the particles. The displayed positive upper region, negative middle region and smaller positive lower region are a common idealization. Temperature and liquid-water conditions can change the sign of graupel charging; some storms have inverted or more complex structures.
Leaders and return strokes differ
A discharge can grow in two directions from an initiation region. For the negative ground flash shown here, the negative end steps toward the ground while a positive end develops in the cloud. Near the ground, an upward connecting discharge completes the path. The bright return-stroke front travels upward; that is not the direction of electron drift. For negative ground lightning, net negative charge is transferred to the ground.
Several different clocks
Cloud electrification develops over minutes. Leaders evolve over milliseconds to tens of milliseconds; a return stroke crosses the channel much faster. The timeline stretches each phase independently and has no single playback-speed factor. A repeat stroke is illustrated for the negative ground flash; real flashes may contain one or several strokes.
Scale and appearance
The main storm uses kilometres for the scene coordinates and an illustrative 13 km cloud top. The upper-atmosphere views retain the altitude scale. Cloud shapes, the landscape and discharge paths are synthetic. Channel width, particle size, charge symbols and faint leaders are enlarged or brightened for visibility. Airflow arrows are qualitative. Polarity does not determine the visible color of a ground flash.
Common names are not always different mechanisms
“Sheet lightning” describes cloud illumination when a channel is obscured. “Heat lightning” is distant lightning whose thunder is not heard. An “anvil crawler” is a branching cloud discharge along an anvil. A “bolt from the blue” can occur with either ground-flash polarity. Ball lightning is not included: its physical explanation remains unsettled.
Sources