What gas makes clouds white and puffy?

Clouds appear white and puffy primarily due to the presence of tiny water droplets or ice crystals that scatter sunlight. This scattering effect is enhanced by the water vapor in the atmosphere, which condenses to form clouds when temperatures drop. The combination of sunlight and these water particles reflects a broad spectrum of light, giving clouds their characteristic white appearance. Thus, while water vapor is crucial, it's the interaction of light with the condensed water that creates the visual effect.