Water vapour absorbs the thermal radiation (heat trying to escape earth) better than it absorbs sunlight (heat trying to enter earth). Therefore, the more water vapour in the atmosphere, the stronger the greenhouse effect.

https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_...

https://en.wikipedia.org/wiki/Greenhouse_effect

They don’t cause net warming, it’s transient. If we stopped flying tomorrow it would go away quickly. But we keep flying.

But even with that the amount of warming this continuous effect creates is quite small and negligible compared to greenhouse gas warming and isn’t really worth talking about.

The difference is that water vapour is a greenhouse gas. IIRC the net warming effect of clouds is a function of altitude.

I have no doubt that nuclear testing has affected the environment far more than is being let on. These experiments by their nature were classified. Who's to say they weren't a factor in helping create the ozone hole?

It's not specifically about logic. It is possible to model and measure the radiative effect of contrails.