1. Unit 5 Lesson 1 What Is the Water Cycle?
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2. Unit 5 Lesson 1 What Is the Water Cycle?
Water on the Move
About three-fourths of Earth’s surface is covered by water.
Water moves between Earth’s surface and the atmosphere through a process called the water cycle.
The sun provides the energy needed for water to move through the water cycle.
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3. Water on the Move Evaporation is the change from a liquid to a gas.
Unit 5 Lesson 1 What Is the Water Cycle?
Water on the Move
Evaporation is the change from a liquid to a gas.
Sunlight heats up water particles near the ocean’s surface, causing water to evaporate.
When water evaporates, it forms an invisible gas called water vapor.
Water can also evaporate from plant leaves through a process called transpiration.
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4. Unit 5 Lesson 1 What Is the Water Cycle?
Water on the Move
The atmosphere is the mixture of gases that surrounds Earth.
Water vapor rises into the atmosphere. In the atmosphere, water vapor cools to form clouds.
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5. Unit 5 Lesson 1 What Is the Water Cycle?
What Goes Up Comes Down
As water vapor rises into the atmosphere, it cools. When water vapor loses enough energy, it condenses to form liquid water.
Condensation is the change of a gas into a liquid.
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6. Unit 5 Lesson 1 What Is the Water Cycle?
What Goes Up Comes Down
Water vapor condenses around tiny particles of salt and dust in the atmosphere to form water droplets.
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7. Unit 5 Lesson 1 What Is the Water Cycle?
What Goes Up Comes Down
When billions of droplets are close together, they form clouds.
Clouds can contain liquid water or ice.
Clouds can form high in the sky or just above the ground in the form of fog.
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8. Unit 5 Lesson 1 What Is the Water Cycle?
What Goes Up Comes Down
As water droplets and snow crystals grow inside clouds, they become too heavy and fall to Earth as precipitation.
Precipitation is water that falls from clouds to Earth’s surface.
Rain, snow, and hail are all forms of precipitation.
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9. Unit 5 Lesson 1 What Is the Water Cycle?
What Goes Up Comes Down
Precipitation that falls into the oceans may quickly evaporate back into the atmosphere.
Precipitation that falls on land may be temporarily stored, it may flow across the land, or it may be used by living things.
Depending on where it falls, water from precipitation may move quickly or slowly through the water cycle.
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10. Unit 5 Lesson 1 What Is the Water Cycle?
Where Does Water Go?
When precipitation occurs, much of the water will not reenter the atmosphere right away.
Some water will seep into the ground.
Water that is stored underground is called groundwater. Groundwater can be found near the surface or very deep underground.
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11. Unit 5 Lesson 1 What Is the Water Cycle?
Where Does Water Go?
How does precipitation get into the ground to become groundwater?
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12. Unit 5 Lesson 1 What Is the Water Cycle?
Where Does Water Go?
Runoff is water that cannot soak into the ground and instead flows across Earth’s surface.
Too much precipitation may cause runoff, which flows into streams, rivers, and lakes.
Runoff may also flood low-lying areas.
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13. Unit 5 Lesson 1 What Is the Water Cycle?
Where Does Water Go?
Precipitation that falls in cold places may become part of a glacier. A glacier is a large, slow-moving mass of ice.
Water can be stored in glaciers for a very long time. Eventually, glaciers will met.
Melting glaciers can increase the amount of runoff in a place.
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14. Where Does Water Go? Describe what is happening in the diagram.
Unit 5 Lesson 1 What Is the Water Cycle?
Where Does Water Go?
Describe what is happening in the diagram.
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15. Unit 5 Lesson 1 What Is the Water Cycle?
A Precious Resource
Fresh water can come from rivers, lakes, and aquifers.
An aquifer is a body of rock that stores groundwater. Aquifers are huge, underground water reservoirs.
The water in an aquifer can run low or be polluted by human activities.
Precipitation adds water to aquifers in places called recharge areas.
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