Sometimes, a cloud is formed very quickly from a mass of very warm, moist air. When this occurs the cloud will become thick and black with condensing water droplets. Once back on the Earth, the cycle can start all over again. The inside of a cloud is actually quite exciting. The wind gusts back and forth in a turbulent manner.
Rain drops condense and tumble about.
It's actually quite chaotic in there. You see, lightning is just electricity on a really big scale. Water droplets and dirt particles in the atmosphere rub up against each other, scraping off stray electrons. Given time, these electrons accumulate in the cloud building up a huge negative electrical charge. When the charge gets large enough the electrons are able to arc to the Earth and reestablish a balance.