The cloud effect is just that. As the shock wave approaches, there is high pressure ahead of it, but low pressure behind it. As the pressure drops, so does the temperature (Boyle’s Law). With lower temperature comes condensation of water, which is visible if the humidity is high enough. That’s what you’re seeing.
You may have seen similar effects before, as in the wingtip vortices visible when jetliners are landing in humid conditions. Same process - pressure drop.
The cloud effect is just that. As the shock wave approaches, there is high pressure ahead of it, but low pressure behind it. As the pressure drops, so does the temperature (Boyle’s Law). With lower temperature comes condensation of water, which is visible if the humidity is high enough. That’s what you’re seeing.
You may have seen similar effects before, as in the wingtip vortices visible when jetliners are landing in humid conditions. Same process - pressure drop.
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Thanks for the technical explanation.