Water evaporated from different sources start moving up in the air through evaporation‚transpiration‚precipitation. When the air moves up it gets cooler and cooler. At sufficient height‚the air becomes cool so that the water vapours present in it condense to form tiny drops of water called droplets. These tiny droplets remain suspended in the air and as they move along with air they combine to form bigger droplets and their size go on increasing‚these droplets become sufficiently larger that they can be seen as clouds.
In this way only the water is evaporated at a large scale.