Contents What is the Water Cycle Our Blue Planet Evaporation FOCUS ON The Amazon Rain Forest Condensation Clouds Precipitation Rainfall FOCUS ON Rain in the Himalayas Accumulation River Basins FOCUS ON The Mississippi River Water Stores FOCUS ON Polar Ice Caps Humans and the Water Cycle Glossary Test Yourself Index 4 6 8 10 12 14 16 18 19 20 22 23 24 26 28 30 31 32
What is the Water Cycle Water on Earth is being constantly recycled through a process called the water cycle This is the movement of water between Earth’s oceans atmosphere and land It has four main stages evaporation condensation precipitation and accumulation Evaporation Condensation Water vapor cools and changes from a gas into tiny liquid droplets in this stage of the water cycle We see this happen in the formation of clouds Water changes from its liquid state to a gas in this part of the water cycle Water evaporates from the oceans lakes rivers and even plants and becomes invisible water vapor in the air Evaporation page 8 Clouds page 14 Clouds contain large amounts of water 4 Water stores page 24
Precipitation As the tiny water droplets that make up clouds get bigger they eventually become so heavy that they escape the cloud and fall as rain If it’s cold enough for the droplets to freeze they fall as snow sleet or hail Rainfall page 18 Water drops fall as rain Accumulation Water that has fallen to the ground as rain sleet snow or hail soaks into the ground or runs over it It gathers in water stores such as lakes or aquifers No matter where it falls it eventually makes its way back to oceans lakes and rivers and the cycle begins again Water accumulates in rivers Transpiration page 11 River basins page 22 5
