I try to understand what the exhaust cloud on the ground from the start of Starship consists of.
Of course it was unusually mineral-rich, but I try to understand whether we saw much else, apart from pulverized launchpad foundation.
Burning methane and oxygen creates water. If that condenses, we have a visible cloud. But it can only condense when it is fairly cold, something below 100 °C (373 K), or in high pressure. It may temporarily condense near shock waves, but that is very local in space and time.
I assume moderate outside temperature. How hot is this big cloud at a rocket launch? Initially, the exhaust is very hot. In other cases, it may be significantly cooled by a water deluge system, that also adds a lot of water, resulting in a big white cloud of condensed water droplets. the Starship launch pad does not have a full water deluge system. It uses a much smaller amount water in a similar way, but I assume I can disregard that in this context.
Shouldn't at least the central part of the exhaust cloud be hot enough to not condense water, and be transparent?
If it should, I assume it was masked by dust from the foundation. No, wait, dust of the foundation.