Water vapor is the gaseous state of water. It is invisible and is formed when water evaporates or sublimates. This process occurs when heat energy is added to liquidwater, causing the watermolecules to move faster and eventually escape into the air as water vapor. Water vapor is a key component of the Earth's atmosphere and plays a crucial role in the water cycle.
Measurement: The amount of water vapor in the air is commonly measured as humidity. Relative humidity indicates the amount of water vapor present in the air compared to the maximum amount the air can hold at a specific temperature.