Water vapor makes up only a few percent of air. There is a limit to how much water vapor air can hold. If that limit is exceeded, then condensation or rainfall occurs. That limit is a law of nature, which applies to all bodies of air,all over the world. The amount of water vapor thatair can hold depends on its temperature.
Warm air can hold more watervapor than cold air.
Within a given parcel of air,the limit can be exceeded and rainfall or condensation triggered, bycooling the parcel of air. In nature, this could happen as the parcel ofair rises. Alternatively, within a given parcel of air, the limit can be exceeded and rainfall or condensationtriggered, by increasing the amount of water vapor in the parcel of air. In nature, this could happen as the parcel of air travels across an oceanor large lake. Drawing on laboratoryobservations to explain an aspect of a natural system.