Science, Tech, Math Science How Much Water Vapor Is in the Earth's Atmosphere? Properties of Water Vapor in the Earth's Atmosphere Share Flipboard Email Print Water vapor can condense to form clouds, but even a cloudless sky contains some invisible water vapor. Anne Helmenstine Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry in Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Updated March 20, 2017 Have you ever wondered how much water vapor is in the Earth's atmosphere or what the maximum amount is that air can hold? Here's the answer to the question. Water vapor exists as an invisible gas in the air. The amount of water vapor in air varies according to the temperature and density of air. The amount of water vapor ranges from a trace amount up to 4% of the mass of air. Hot air can hold more water vapor than cold air, so the amount of water vapor is highest in hot, tropical areas and lowest in cold, polar regions. Learn More Most Abundant Gas in the Earth's AtmosphereChemical Composition of AirWater Facts and PropertiesDensity of AirWhat Is the Greenhouse Effect? Continue Reading