What Is Water Vapor?

Water vapor is the gaseous form of water that permeates the Earth's atmosphere. This moist gas affects the Earth by altering the world's overall climate. The hydrologic cycle demonstrates how water becomes vapor. This cycle documents the change of water from gas to liquid to solid states.

The majority of the Earth is covered in ocean water. As the sun strikes the ocean's surface, water evaporates upward to create water vapor. This vapor forms clouds and possible rain storms. Water vapor condenses from the rain storm clouds, forming water droplets that fall onto the Earth's landforms. The vapor can also be excessively cooled while in the atmosphere, creating hail, ice, or snow.

This vapor is an essential component to creating rainfall across dry land areas. Plants and animals would not be able to survive without a water supply from the sky, filling lakes and rivers for consumption. Desert areas, with little or no rain, are good examples of how the world would appear if water vapor did not contribute to rainfall.

Vapor produces the humid and sticky effect felt on hot days. Tropical climates, such as those near the Earth's equator, have consistently warm days. The sun's warmth draws more moisture from the nearby ocean, forming more water vapor and producing excessive humidity levels in that region.

Excessive water vapor, or high humidity, can cause a person to feel as if he or she cannot breathe. During high humidity, water molecules within the air are more densely packed together. As a result, a person may feel the weight of the moist air, compared to a dry air climate. People living in high humidity areas tend to use air conditioning machines to remove the moist water droplets and cool the resulting dry air.

Many people use water vapor in the home in the form of an appliance, called a humidifier. This device generates vapor to moisten dry air within a room or home. Breathing problems can occur in people with preexisting lung problems and skin can easily crack with consistent dry air, especially during the winter months. Humidifiers are also helpful in combatting colds as they ease any coughing fits that may occur.

Studies have suggested that water vapor is contributing to global warming. The moist air is thought to form a blanket across the Earth's surface, and prevent heat from escaping into space. As a result, the world may possibly become even warmer. The excessive atmospheric heat may create more evaporation, exacerbating the global warming problem with further water vapor accumulation.