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What is water cycle?

The water cycle, also known as the hydrologic cycle, is the continuous movement of water on, above, and below the Earth’s surface. It is the process by which water is cycled and recycled throughout the Earth’s atmosphere and ecosystems.

Water states of matter

Water exists in three different states of matter as below:

Solid State

Ice is water that has solidified. Water molecules are tightly packed together in this state, forming a crystalline structure. The temperature at which water freezes to become ice is 0°C (32°F) at standard atmospheric pressure.

Liquid State

Water in the liquid state is the form of water that we are most familiar with. In this state, water molecules are free to move around and slide past each other, allowing it to take the shape of its container. The temperature at which water boils to become a gas is 100°C (212°F) at standard atmospheric pressure.

Gas State

Water vapor is the gaseous state of water. Water molecules are widely separated and moving rapidly in all directions in this state. Water vapor is invisible to the naked eye, but when it condenses into tiny droplets to form clouds or fog, it can be seen. The dew point is the temperature at which water vapor condenses to become a liquid, and it varies depending on the amount of water vapor in the air.

Steps of the water cycle


Water evaporates from the Earth’s surface, including oceans, rivers, lakes, and even soil and plants, due to the sun’s heat energy.


Plants also release water vapor through tiny pores in their leaves, a process known as transpiration.


As water vapor rises into the atmosphere, it cools and condenses into tiny droplets to form clouds.


When the droplets in clouds become too heavy, they fall back to the Earth’s surface as precipitation, including rain, snow, sleet, and hail.


Precipitation that falls on land is absorbed into the ground through a process called infiltration.


Excess precipitation that cannot be absorbed into the ground flows over the surface of the land, creating streams, rivers, and eventually, oceans.


Some of the water that infiltrates into the ground is stored as groundwater, which can be used by plants or seep back into rivers and lakes.

Water cycle diagram

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Process of the water cycle

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The water cycle is a natural process that describes the ever-present movement of water on Earth. The process begins with the evaporation of water from oceans, rivers, and lakes, as well as transpiration from plants. This water vapor rises into the atmosphere and condenses into clouds as it cools. As the clouds grow and become heavier, the water droplets combine and fall back to the Earth’s surface as precipitation, such as rain, snow, or sleet. The precipitation can be intercepted by vegetation, run off into rivers and streams, or infiltrate into the soil, where it can be taken up by plants or recharge underground aquifers. Some of the water may also evaporate directly back into the atmosphere, completing the cycle. The water cycle is a vital process for sustaining life on Earth, and it is influenced by various factors such as climate, topography, and human activities.

Importance of water cycle

The importance of the water cycle cannot be overstated. It plays a vital role in regulating the Earth’s temperature and weather patterns, providing a consistent supply of freshwater to support all forms of life, and maintaining healthy ecosystems. The water cycle also helps in the distribution of nutrients and minerals throughout the soil, as well as the support of agricultural production and the generation of energy via hydropower.

What is percolation water cycle

The percolation water cycle is a part of the overall water cycle that describes the movement of water from the surface of the Earth into the ground. It is also known as the infiltration water cycle or groundwater cycle.

Water from precipitation or other sources, such as lakes, rivers, or streams, percolates through the soil surface, rock layers, or other porous materials and fills the empty spaces or pores within them during the percolation cycle. This is known as infiltration.

Once the water reaches the soil or rock layers, it moves downward due to the force of gravity, following the path of least resistance. This downward movement of water is known as percolation.

As the water percolates through the ground, it may be stored temporarily in porous rock layers or underground aquifers, where it is available to be used by plants or drawn up by wells. Some of the water may also continue to flow deeper into the ground, eventually reaching the water table, which is the upper surface of the groundwater reservoir.

The water may be discharged from the groundwater reservoir into springs, rivers, lakes, or oceans, completing the water cycle.

The percolation water cycle plays an important role in replenishing groundwater reserves, supporting plant growth, and sustaining ecosystems. It is also essential for human activities such as agriculture, industry, and domestic water supply.

Water cycle work sheet

Label the different parts of the water cycle diagram below.


A – Precipitation

B – Condensation

C – Evaporation

D – Collection


What is evaporation?

Answer: Evaporation is the process by which water is converted from a liquid state to a gaseous state due to heat.

What is condensation?

Answer: Condensation is the process by which water vapor in the air is converted into liquid water due to cooling.

What is precipitation?

Answer: Precipitation is any form of water that falls from the clouds to the ground. This includes rain, snow, sleet, as well as hail.

What is collection?

Answer: Collection is the process by which water is gathered in lakes, rivers, and oceans after it falls to the ground as precipitation.

How does the water cycle help maintain life on Earth?

Answer: The water cycle helps maintain life on Earth by providing fresh water for plants and animals to drink, and by replenishing water sources that are used for irrigation and other purposes. Without the water cycle, life on Earth would not be sustainable.

Water cycle work sheet 1

Water cycle work sheet 2

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Anuradhika Lakmali

Anuradhika Lakmali is a co-founder of Science A Plus learning network. She is working as a government teacher and has interest in chemistry, biology, phisics and self development.