The circulation and redistribution of water between the atmosphere and Earth is known as the hydrological (or water) cycle. This cycle is a continuous process involving the movement of water in various forms—liquid, vapor, and ice—between the oceans, atmosphere, land, and living organisms. The process is driven by solar energy and gravity, playing a crucial role in sustaining life by regulating temperature, shaping weather patterns, and supporting ecosystems. Below is a description of each major step in the cycle, along with an explanation of how water moves through each phase.

Steps of the Hydrological Cycle

Evaporation and Transpiration:

Evaporation occurs when solar energy heats surface water (from oceans, lakes, rivers, etc.), causing it to transform from liquid into water vapor and rise into the atmosphere.
Transpiration is the process by which plants release water vapor from their leaves into the atmosphere. Together, evaporation and transpiration are called evapotranspiration.

Condensation:

As water vapor rises, it cools and transforms back into liquid droplets, forming clouds through condensation. Dust particles in the atmosphere aid in the condensation process, providing surfaces for water molecules to attach.

Precipitation:

When water droplets in clouds combine and grow large enough, they fall back to Earth’s surface as precipitation in the form of rain, snow, sleet, or hail, depending on temperature and atmospheric conditions.

Infiltration and Percolation:

Some of the precipitation that reaches the ground infiltrates the soil in a process known as infiltration. Water that moves deeper into the soil reaches the groundwater zone through percolation.

Runoff:

The water that does not infiltrate or percolate into the ground flows over the land surface as runoff. Runoff collects in rivers, streams, and eventually flows into larger bodies of water, like lakes and oceans. Runoff also carries nutrients, sediments, and other materials along its path.

Groundwater Flow:

Water that infiltrates into the soil can also flow underground as groundwater flow and may eventually reach rivers, lakes, or oceans, completing its path through the hydrological cycle.

Sublimation and Desublimation (Less Common Processes):

Sublimation is the direct transformation of ice (from glaciers or snow) into water vapor without passing through the liquid phase, which occurs in colder regions. The opposite process, desublimation, occurs when water vapor directly turns into ice.

Summary of the Water Cycle Process

The hydrological cycle is a closed system, meaning water continually circulates without leaving or entering from outside. Water evaporates, forms clouds, precipitates back to Earth, infiltrates soil, flows as runoff or groundwater, and eventually returns to larger water bodies, where it evaporates again.

Sketch of the Water Cycle

To illustrate the water cycle effectively, you can include the following elements in a sketch:

Oceans, Lakes, and Rivers: Showing the primary sources of evaporation.
Sun: Representing solar energy, which powers the cycle.
Evaporation and Transpiration Arrows: Rising from oceans, plants, and other water bodies to the atmosphere.
Clouds: Formed by condensation, ready to precipitate.
Precipitation Arrows: Falling from clouds to the Earth’s surface as rain or snow.
Infiltration and Groundwater: Showing water penetrating the soil and moving underground.
Runoff Arrows: Indicating the movement of water across the land toward rivers and oceans.
Mountains and Glaciers (optional): Depicting sublimation where applicable.

This sketch highlights the cycle’s key processes and showcases how interconnected each element is, emphasizing the balance and recycling of Earth’s water supply.