Water Cycle: The Bio-Geochemical Cycle

What is the Water Cycle?

The reason behind the rain, cloud, etc. can be understood by studying the biogeochemical cycle also called as the water cycle or hydrological cycle. The water cycle is a multi-phase journey in which the water molecules from the earth surface make their way towards the atmosphere and return. Sun could be called as the powerhouse which initiates this process. There is a continuous exchange of moisture from the water bodies, atmosphere, and the land surface.

Water Cycle The Bio Geochemical Cycle

Water Cycle Process

Most of the moisture found in our atmosphere is a result of evaporation that occurs from oceans, seas, lakes, etc. Evaporation is a process in which the water changes from liquid phase to gaseous phase. Plants also play a role in releasing the moisture through the process of transpiration. Plants take in water from the ground through their roots and release them into the atmosphere, with the help of small pores present on the leaves. Sublimation of snow also results in the formation of vapor to a certain extent. Therefore, evaporation, sublimation, and transpiration together are responsible for the water vapor present in the atmosphere.

As water vapors find their way into the lower atmosphere, the air currents raise them up into the higher atmosphere. They undergo condensation there. Condensation is a process in which matter changes its state from gaseous phase to liquid phase. Due to condensation and the atmospheric conditions, the vapors get converted into a precipitate such as snow, rain, sleet, or hail. This is the primary system involved in transporting water back to the earth’s surface.

Once the precipitate falls on the surface of the earth, it takes various paths. Some of the precipitates get evaporated. Others seep into the ground while some flow into oceans, rivers, and streams.

Hence, the hydrological cycle repeats itself continuously. A simple diagram of the water cycle is shown below: