The mechanism of lightning can potentially be well explained by processes consistent with variations in hydrogen electron orbitals due to: (i) atmospheric pressure changes, and (ii) water phase changes.

Type (i) - Downward Current Lightning

In storms, rising water vapour travels rapidly from the lower atmosphere (at a higher pressure) towards the upper atmosphere (at a lower pressure). This drop in pressure allows for an increase in the average hydrogen electron orbital size (i.e. more hydrogen atoms are now in excited states). Expansion is  endothermic and also creates an "electron energy demand". This demand can build up to the extent that the voltage difference is enough to overcome atmospheric resistance, causing electrons to be released from the earth's surface as lighting. Electrons travel upwards towards the upper atmosphere, satisfying the "electron energy demand".

A potential source of the electron energy released from the earth's surface is the contraction of electron orbitals, including contraction of hydrogen electrons to de-excited states. Electron contraction is exothermic with quantised energy releases expected in the extreme ultra-violet and x-ray parts of the electromagnetic spectrum. Reported x-ray emissions observations eminating directly from the lighting impact point (Lovett, 2014), are consistent with the localised formation of de-excited electrons at the lightning impact point.

The formation of de-excited hydrogen may also facilitate secondary transmutation processes, via de-excited hydrogen addition reactions. Lightning transmutation observations, such as strong sulfur smells in the vicinity of the lightning strike point, have been reported historically.

Type (ii) - Upward Current Lightning

Lightning may also occur due to a downwards flow of electrons.  The phase change of water vapor to liquid water is expected to result in a contraction of the hydrogen electron orbital size, resulting in an excess of electron potential energy.  When large amounts of water vapour condense, significant excess energy can be accumulated that can be suffiecient to allow electron transfer to the earth as lightning.

Example: Type (i) Lightning Caused by Rising Water Vapour

S. Brink 17-8-17 

Lovett, R, 2014, Lightning Captured by X-Ray Camera - A First, National Geographic News, available online at: