I think the term “weight” - while useful at sea level - can easily confuse people when it comes to clouds, as the density of the water in a cloud doesn’t have much to do with the weight of the cloud - see my elaborated edited response (unless I mis-guesstimated) - the mass of a cloud changes so drastically with altitude that the relative or even the absolute weight of water (vapor) therein is going to give people the wrong idea.