The water cycle

In your book, Our Wondrous World (Chapter 1), there is an activity with a transparent bag. You draw the Sun, clouds and trees on it, fill one-third of it with coloured water, seal it tightly and put it in the sunlight. After a few hours, the Sun's heat turns some of the water into water vapour. When the vapour cools, it forms small droplets inside the bag, and the droplets fall back down.

The same thing happens in nature, in this order. First, the Sun's heat turns water from oceans, rivers and other sources into water vapour. Next, the water vapour forms clouds. Then the clouds come down as rain, snow and hail. Last, this water goes back into rivers, lakes and oceans.

Then it all begins again! This constant circular movement of water in nature is called the water cycle. As it travels through the air, land and sky, water keeps changing its form.