The Water Cycle (explained in 2 minutes)
Evaporation, transpiration, condensation and precipitation explained with a puddle that becomes rain, plus groundwater, ice and why water never disappears.
- Subject: Science
- Age group: 10-14
What this video covers
- Water moves repeatedly among Earth's ground, air, rivers, lakes, and oceans, changing between liquid, gas, and solid states.
- Sun-warmed liquid water becomes rising water vapour, while plants release water vapour through their leaves.
- Cooling water vapour changes into tiny liquid drops that gather into clouds.
- A puddle after rain follows the first stages of the water cycle: warming, evaporation, rising, cooling, and condensation into cloud droplets.
- Wind carries clouds over hills, gravity brings heavy droplets down as precipitation, and flowing rain travels through streams and rivers to the sea.
- Some rain enters soil and rock as groundwater, plants use some of it, and some returns to the air through transpiration.
- Precipitation may be snow or hail, water can remain frozen in glaciers or snowfields, and melting ice flows or enters the ground.
- Water may be stored temporarily, but energy and gravity keep changing its form and location, supplying fresh water while oceans hold most of Earth's water.
- A familiar puddle invites the learner to predict the next place its water may travel.
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Transcript
Water on Earth is always moving in a repeating journey called the water cycle. It travels between the ground, the air, rivers, lakes, and oceans. The same water may be liquid, a gas called water vapour, or a solid such as ice. Energy from the Sun helps drive this journey.
When the Sun warms water in a puddle, lake, or ocean, some liquid water changes into invisible water vapour and rises. This change is called evaporation. Plants also release water vapour through tiny openings in their leaves; that process is called transpiration.
Higher in the atmosphere, the air is cooler. Water vapour cools and changes into tiny liquid drops. This is condensation, and the drops gather to form clouds.
Here is one worked example. Imagine a puddle left after a rainstorm. First, sunlight warms it, so some of its water evaporates. The vapour rises and cools, then condenses into droplets in a cloud.
Winds may carry that cloud over a hill. When the droplets join together and become heavy, gravity pulls them down as precipitation, such as rain. Some rain flows downhill into a stream, which carries it to a river and eventually the sea.
Some soaks into the soil, moving through spaces between soil and rock as groundwater. Plants can use some of that water, and some can later return to the air through transpiration.
Precipitation can also fall as snow or hail. In cold places, water may stay frozen in glaciers or snowfields for a long time. When ice melts, the water flows or soaks into the ground.
Water can be stored temporarily in many places, but it does not disappear. It keeps changing form and location as energy and gravity move it around. This cycle supplies fresh water for people, animals, and plants, while oceans hold most of Earth's water.
Next time you see a puddle, try to predict where its water could travel next.