Water is the basic element of nature. It is required by every forms of life on the Earth. Water covers 70% of the earth’s surface. It provides life, eases out heat, drains harmful substances and mediates many day-to-day works. Water needs to be replenished, purified and circulated again and again so that it can perform its functions. Nature does this job through a process called the water cycle.

The water cycle, also known as the hydrologic cycle or the hydrological cycle, describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another such as from river to ocean or from the ocean to the atmosphere, by the physical processes of evaporation, condensation,  precipitation, infiltration, surface runoff and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor.

So, how does this cycle works? When the sun shines, the water from the ocean or lake evaporates due to heat from the sun. When it evaporates, it turns into water vapor and goes up into the atmosphere. This water vapor gets together with other water vapor and turns into a cloud. When clouds get dense, they drop the water back to Earth in some form of precipitation like rain, snow, hail or sleet. When the water falls back down to the Earth, they find their way on the ground surface into puddles, streams and rivers. Again this water will evaporate and the whole cycle will start again

The evaporative phase of the cycle purifies water which then replenishes the land with freshwater. The flow of liquid water and ice transports minerals across the globe. It is also involved in reshaping the geological features of the Earth, through processes including erosion and sedimentation. The water cycle is also essential for the maintenance of most life and ecosystems on the planet.

The water cycle has many effects: it regulates the temperature of the surroundings. It changes weather and creates rain. It helps in conversion of rocks to soil. It circulates important minerals through the spheres. It also creates the many geographical features present on earth like the ice caps of mountains, icebergs, the rivers and the valleys, lakes, and more. Hence it is quite important to understand and learn the processes of the water cycle.