Why do clouds float?

Clouds float in the sky

... because they are less dense than the surrounding dry air at sea level:

• The density of clouds (containing water vapor and some ice particles) = 1.003 kg/m³
• The density of dry air at sea level = 1.2 kg/m³

Because the latter is a higher value than the former, clouds float in the sky just like a heavy cruise ship on sea water!