Unit 1 Lesson 3

Unit 1 Lesson 3 The Water Cycle What is the water cycle? ~70% of the Earth’s surface is covered by oceans, and salt water makes up about 97% of the Earth’s total volume of water. Only 3% of Earth’s water is fresh water, and 2.5% of that is unavailable: either locked up in glaciers, polar ice caps, atmosphere or soil; highly polluted; or lies too far under the earth's surface to be extracted at an affordable cost. This means that only 0.5% of fresh water on Earth is readily available for us to use. 2

Unit 1 Lesson 3 The Water Cycle What is the water cycle? The movement of water between the atmosphere, land, ocean, and living things makes up the water cycle. The water cycle moves energy and matter. Energy is transported by changes in state and by the movement of water from place to place. 3

Transportation of matter in the water cycle. Unit 1 Lesson 3 The Water Cycle Transportation of matter in the water cycle. Matter is transported all around the world by ocean currents, rivers, and glaciers. Rain, snow, sleet and hail fall from the atmosphere onto the oceans and land. On land, ice and water flow downhill into large bodies of water like lakes, seas and oceans. Water vapor moves upward into the atmosphere and is carried great distances by the wind. The wind also creates ocean currents. 4

How does water reach the atmosphere? Unit 1 Lesson 3 The Water Cycle How does water reach the atmosphere? Water reaches the atmosphere as water vapor through evaporation, transpiration, and sublimation. Evaporation occurs when liquid water changes to water vapor. Most of the water vapor in the atmosphere evaporates from Earth’s oceans. 5

How does water reach the atmosphere? Unit 1 Lesson 3 The Water Cycle How does water reach the atmosphere? Transpiration is the release of water vapor into the atmosphere by plants. Sublimation is when solid water changes directly to water vapor without first becoming a liquid. Sublimation can occur when dry air blows over ice or snow, where it is very cold and the pressure is low. This can also be seen in freezers. 6

How does water reach the atmosphere? Unit 1 Lesson 3 The Water Cycle How does water reach the atmosphere? Identify each process as evaporation, sublimation, or transpiration. Evaporation Transpiration Sublimation 7

How does water go from the atmosphere to the surface? Unit 1 Lesson 3 The Water Cycle How does water go from the atmosphere to the surface? Condensation is the change of state from gas to liquid. It can occur in the air as clouds, fog, or mist, or on the ground as dew. Deposition is the change of state from a gas, directly to a solid. It occurs when water vapor changes directly into ice, like frost or snowflakes. Precipitation is any form of water that falls to Earth from clouds. Rain, snow, sleet and hail are common forms of precipitation. 8

Particle Movement in Different States of Matter Solid Liquid When water particles absorb or gain energy, they move faster and farther apart. When water particles release or lose energy, they move slower and closer together. Gas

How does water change state? (energy gains) Unit 1 Lesson 3 The Water Cycle How does water change state? (energy gains) Water on Earth is found as a liquid, solid, and gas. All changes of state are physical changes. Water absorbs or gains energy from its surroundings as it melts from solid to liquid. Water also absorbs or gains energy as it evaporates from liquid to gas, or when it sublimates from solid to gas. 10

How does water change state? (energy losses) Unit 1 Lesson 3 The Water Cycle How does water change state? (energy losses) Water releases or loses energy to its surroundings when it condenses from gas to liquid. Water also releases or loses energy when it freezes from liquid to solid or deposits from gas to solid. No water is lost during any changes of state. 11

How does water move on land and in the oceans? Unit 1 Lesson 3 The Water Cycle How does water move on land and in the oceans? Streams, rivers, and the water that flows over land are types of runoff. Runoff flows downhill. Some of the water on land seeps into the ground. This process is called infiltration. Once underground, the water is called groundwater. Groundwater also flows downhill. 12

Runoff Infiltration Groundwater

How does water move on land and in the oceans? Unit 1 Lesson 3 The Water Cycle How does water move on land and in the oceans? Glaciers, sometimes called “rivers of ice”, flow downhill and sometimes flow to the ocean, where pieces may break off. Winds move ocean water on the surface in great currents over long distances. Cold water will sink in the ocean and move towards the warmer areas at the equator. This movement forms deep ocean currents (the movement of ocean water in a particular direction and pattern) that move large amounts of water. 14

Not to Scale