00 / SHORT ANSWER
Ball lightning is a reported luminous event with evidence, not a solved single story
Picture a storm after the main flash: a glowing bead appears low over the ground, drifts for a few seconds, and fades before the eye can decide whether it was a reflection. “Ball lightning” names that family of reports. The careful answer has two halves: some events have been observed and recorded with useful detail; the physical mechanism that makes the whole pattern remains open.
Start with the Ball lightning evidence dial. It lets you move through the layers without treating a vivid description, a spectrum, and a complete theory as the same kind of evidence.
01 / THE OBSERVATION
A small bright object can be a real observation and still be hard to classify
Bright and near the ground
Weather-service summaries describe a rare, bright, ball-like object reported close to the ground, often during or after thunderstorms.
Seconds matter
Duration, motion, apparent size, colour, and the time relative to a lightning strike are the details that turn an anecdote into a record.
Storm context helps
A report becomes more informative when the observer records nearby strikes, rain, wind, buildings, power lines, and the camera position.
Appearance is not chemistry
A colour impression can suggest a hypothesis. It cannot identify a chemical composition or establish a unique mechanism on its own.
02 / THE SPECTRUM
The important leap is from “I saw a glow” to “the light carried a signature”
A Physical Review Letters field observation reported video and a spectrum from a luminous event after a cloud-to-ground lightning strike. The spectrum included emission lines associated with elements in soil, including silicon, iron, and calcium. That result gives researchers a physical clue to test: material from the ground may have entered the glowing event.
It still does not choose the final model. A mechanism must account for the light, the observed lifetime, the movement, the size, the storm relationship, and the chemical signatures together. The right scientific mood is a bright exclamation mark followed by a careful question mark.
A spectrum narrows the room. It does not automatically tell us which guest turned on the light.
EVIDENCE DIAL / BALL LIGHTNING
把“神秘”转成四层证据
拖动旋钮，看看一个现象怎样从目击描述走到可检验的开放问题。证据越多，边界越清楚；机制仍然需要单独证明。
键盘操作：聚焦滑杆后使用方向键，在“看见了什么”和“还缺什么机制”之间移动。
A spectrum
The 2014 Physical Review Letters observation reported emission lines associated with elements in soil after a cloud-to-ground strike.
03 / PLASMA, WITH A CAVEAT
Plasma is a useful family resemblance, not a finished explanation
The U.S. Department of Energy describes lightning and ball lightning among examples of luminous plasma phenomena. That vocabulary helps explain why a hot, glowing, partially ionised state belongs in the conversation. It does not prove that every report shares one plasma process, or that naming plasma has solved the event.
A responsible answer keeps three labels visible: observed, supported, and still open. That small discipline protects the wonder. The glowing bead remains strange; the record around it becomes sharper.
04 / SOURCES
Primary and authoritative sources used here
Physical Review Letters
Observation of the Optical and Spectral Characteristics of Ball Lightning
Reports a luminous object after a thunderstorm strike, its motion and duration, and spectral lines associated with silicon, iron, and calcium.National Weather Service
Spring Science: Lightning types and rare phenomena
Describes ball lightning as rare and random, often reported as an orange or reddish luminous sphere near the ground.U.S. Department of Energy
DOE Explains...Plasma
Explains ionised plasma and lists ball lightning as a type of lightning plasma without claiming a complete formation mechanism.American Physical Society
First Spectrum of Ball Lightning
Provides physics context for what the spectral evidence supports and what it leaves unresolved.This page separates evidence from interpretation. The dial is an educational aid, not a claim that one mechanism has been confirmed.