Water Cycle 

Water is the most important natural resource found on the Earth. It is the reason for the sustainment of life on the Earth. It plays an important role not only in various biological processes activities such as digestion and transportation of nutrients but also in non-biological activities, which include the sowing of fields, supporting ecosystems, etc. The water cycle is a simple but essential aspect of this element, ensuring the continuous process of water through different stages. This article describes the water cycle in detail to help you understand every aspect of this simple yet important atmospheric process.

1.0Description of the Water Cycle

The Water Cycle, also named the hydrologic water cycle, is the continuous movement of water from Earth to the atmosphere and from the atmosphere to Earth. The sun is the ultimate source of processes related to the water cycle. The Energy of the sun converts the water into its different states that are liquid, gas, and solid present on the surface of the Earth. To understand the water cycle, it is important to consider each step, from evaporation to precipitation. The cycle continues with runoff and infiltration, ensuring that the water is constantly moving through different stages and supporting ecosystems.

2.0Key Processes of the Water Cycle

The water cycle is not a process involving only one activity, but it is the collection of different processes, which include: 

1. Evaporation:  

Description: Evaporation is the conversion of water from its liquid to gaseous form when heated by the sunlight. Evaporation in the water cycle is the primary process which happens in oceans, lakes, rivers, and other water bodies under the influence of the sun. 

What Happens: The sun's heat provides energy, and it propels the molecules of water to move much more quickly than they otherwise would, such that some break free from the surface. These rise into the atmosphere as water vapour. 

2. Transpiration: 

Description: Transpiration is the release of water vapours from the pores present in the leaves of the plants into the atmosphere. 

What Happens: Plants absorb water from the soil through the roots. This water moves throughout the plant until it finds its way out of the tiny openings on the underside of leaves called stomata. 

3. Condensation: 

Description: Condensation is the cooling down of water vapour and then converting it into liquid droplets, which helps in forming clouds. 

What Happens: When the water molecules rise into cooler areas of the atmosphere, the heat energy drains off, making the molecules slow down and turn into droplets in tiny forms, which then start combining into clumps, giving the appearance of clouds. 

4. Precipitation: 

Description: When it becomes tough for water droplets to remain suspended in the clouds due to being heavy, they fall back on the Earth’s surface. 

What Happens: When the water droplets or ice crystals in the clouds combine and grow large enough, they fall as rain, snow, hail, or sleet due to gravity. 

5. Runoff: 

Description: It is the process of flowing water over the surface and then returning to large water bodies such as rivers, oceans, and lakes. 

What Happens: Once it has precipitated, if the ground is saturated or if there is water that needs to be absorbed into the soil, it flows across the surface as runoff. Runoff is important in transporting water across land and completing the water cycle.

6. Infiltration/Percolation:

Description: Infiltration and percolation are the processes that help in the downward travelling of water from the surface/ground to replenish underground water. 

What happens: Precipitation or runoff also leads to infiltration, that is, soaking into the soil. It will seep down through the soil layers and rocks into underground storage tanks called aquifers. 

3.0Water Cycle Drawing

Drawing of the water cycle helps the students visualise the concept of the water cycle, explaining the water cycle quickly and easily. 

4.0Types of the Water Cycle

The water cycle can be classified into two types of water cycles that are: 

1. Biological Water Cycle: As suggested by the name it is the type of water cycle which involves processes through the living organisms and ecosystems. It involves focusing on the absorption and release of water through plants and animals from the atmosphere via the processes of transpiration and respiration. 
2. Global Water Cycle: It involves the movement of water from the whole planet via the processes mentioned above. It involves the constant movement of water in the atmosphere, hydrosphere, and lithosphere at the global scale; it moves water from oceans to land and back to the atmosphere.

5.0Modelling the Water Cycle

Modeling the water cycle is a fun and efficient method of showing the students how water moves from one stage to another in the water cycle. By acting out the processes of evaporation, condensation, precipitation, and runoff, hands-on activities engage and visualise concepts that are not so easily remembered in a lecture or textbook format.

Divide into groups and simulate the water molecule, acting out stages of the water cycle - evaporation, condensation, and precipitation. Set up the classroom as Earth's surface, so there are regions for the ocean, land, and clouds. The "sun" heats the ocean to evaporate those molecules into forming clouds, finally precipitating the water back out as rain or snow.