The gaseous phase of substances such as water. Water vapor is largely invisible, and in the off-chances that you notice a foggy, cloudy, or misty texture then it is most likely liquid water and not water vapor. The climate and weather are highly dependent on water vapor, since without it there would be formations of clouds, or occurrences of snow or rain, which all need water vapors to form. The evaporation of water vapor throughout earth’s surface leads to the formation of precipitation via snow or rainfall. The earth is also kept warm enough to support its inhabitants through natural greenhouse effect provided by water vapors.