Science, Tech, Math › Science Water Vapor in the Earth's Atmosphere Share Flipboard Email Print Ekaterina Nosenko/Getty Images 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. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College 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. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated March 16, 2019 Have you ever wondered how much water vapor is in the Earth's atmosphere or what the maximum amount is that air can hold? How Much Water Vapor Is in the Earth's Atmosphere? 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.