The water cycle © 2009 Marshall Cavendish International (Singapore) Private Limited

Questions to think about… What are the roles of evaporation and condensation in the water cycle? What is the importance of the water cycle? What is the water cycle? © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle Water falls from the sky as rain. Some of the rain falls into water bodies such as rivers, ponds and seas. Some of it seeps into the ground. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle When the Sun appears, heat from the Sun causes the water in the water bodies to evaporate. The same happens to puddles of water formed after it rains. Water is also returned to the air when living things give out water vapour and when water evaporates from their bodies. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle The water vapour mixes with the surrounding air, and is taken up with warm air as it rises into the sky. As the warm air rises, it cools and condenses into tiny water droplets. These droplets group to form clouds in the sky, just like the white ‘clouds’ formed around the spout of a kettle of boiling water. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle As the clouds rise higher in the sky, their surroundings become colder. As a result, more water vapour condenses. The tiny droplets of water in the clouds combine to form bigger droplets. Soon, these water droplets become too big and heavy, and fall back to Earth as rain. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle Rain that falls onto the ground goes into the soil. Plants take in this water through their roots. Rainwater also collects in seas, rivers, ponds and reservoirs. Animal and people get water from some of these places. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle Water collected in reservoirs is sent to water treatment plants for purification. After water is purified, it is then sent to your home. The water you get at home is safe for drinking, cooking and washing. © 2009 Marshall Cavendish International (Singapore) Private Limited

The water cycle After water is returned to the Earth, it starts to evaporate again. The movement of water between the Earth and the sky happens repeatedly in a cycle. This is known as the water cycle. © 2009 Marshall Cavendish International (Singapore) Private Limited

Roles of evaporation and condensation Water vapour rises into the sky. Water evaporates from living things Water evaporates from water bodies. Water evaporates from the ground. © 2009 Marshall Cavendish International (Singapore) Private Limited

Roles of evaporation and condensation Water vapour cools and condenses to form clouds. Water droplets fall from the clouds as rain. Rain falls onto the land or is collected in water bodies. © 2009 Marshall Cavendish International (Singapore) Private Limited

Importance of the water cycle The water cycle occurs because water can change from one state to another. This cycle is important to all living things on Earth. It makes sure that there is a never-ending supply of water for the survival of all living things. © 2009 Marshall Cavendish International (Singapore) Private Limited

The end © 2009 Marshall Cavendish International (Singapore) Private Limited