The Hydrosphere and Biosphere

1. The Hydrosphere and Biosphere Why is water so important to life? Where can we find life on Earth?

2. The Hydrosphere • The hydrosphere includes: • The water on or near the Earth’s surface • All glaciers and icecaps • The water found in rock beneath the Earth’s surface • The clouds in the sky

3. The Water Cycle • Water is constantly being cycled from the ocean to the air, then on land, and then back again. • This process is the water cycle.

4. The Water Cycle • First, water evaporates from the Earth’s surface, forming clouds. • The majority of this water comes from the oceans. • Then, the water condenses, combining with dust to form droplets.

5. The Water Cycle • Next, the droplets become heavy enough to fall back to Earth – a process we call precipitation. • Includes rain, snow, sleet and hail.

6. The Water Cycle • Finally, precipitation becomes runoff, and may either: • Collect in freshwater storage (lakes, ponds, etc.) • Becomes groundwater • Returns to the ocean

7. Earth’s Oceans • Technically, the Earth’s oceans are all united into one joint ocean. Geographically, however, the joint ocean is divided into five smaller oceans. Together, they cover 70% of the Earth’s surface. • From largest to smallest: Pacific, Atlantic, Indian, Southern (around Antarctica), Artic.

8. Earth’s Oceans • Ocean water is laden with salt and other solutes. This is due to erosion and deposition, as well as underwater eruptions. • The majority of these solutes is sodium chloride (table salt). • The salt content of the ocean is 3.5% of the ocean’s weight. It’s enough to severely dehydrate and kill anyone who drinks it.

9. Earth’s Oceans • Note that the oceans are less salty in areas that get a lot of rain, or that receive freshwater. • Also, the oceans are saltier in areas where water evaporates rapidly. • Why?

10. Earth’s Oceans • The ocean can be divided into three areas based on relative temperature. • Surface zone • Thermocline • Deep water

11. Earth’s Oceans • Light only penetrates so deep, so only the top layer is relatively warm. • Temperature drops dramatically in the thermocline layer. • The deep zone is very dark and cold.

12. Earth’s Oceans • The oceans are critical for regulating the Earth’s temperature. • The ocean absorbs more than half the solar radiation that reaches the surface.

13. Earth’s Oceans • Due to water’s high specific heat, it absorbs and releases heat much more slowly than the ground does. • This keeps the Earth’s temperature relatively constant.

14. Exit Ticket • Name all four types of precipitation. • Most of the water vapor in clouds came from the _____. • Runoff (fallen precipitation) ends up in three possible places. Name them. • In which layer of the ocean does temperature drop the fastest? • How does the ocean moderate Earth’s temperature?

15. Ocean Currents • Ocean currents are the motions of water. • Both surface and deep currents exist. • Surface currents happen at or near the surface, and are wind-driven.

16. Ocean Currents • Surface currents may be warm- or cold-water currents. Currents of widely differing temperature do NOT readily mix. • This means that a warm-water current can maintain its temperature over long distances.

17. Ocean Currents • Note that surface currents can affect local temperatures, depending on whether they are warm or cold. • Warm currents tend to make moderate climates, and cold currents lower temperatures.

18. Ocean Currents • For instance, the Scilly Isles (England) and Newfoundland (Canada) are at similar latitudes, but the Scilly Isles are far warmer, due to the presence of a warm water current.

19. Ocean Currents • Deep currents are very slow, stream-like water movements along the ocean floor. • When cold, dense water sinks under warm water, these currents form.

20. Fresh Water • About 3% of the Earth’s water is fresh water, but much of that is frozen in large glaciers. • The remainder is found in surface freshwater and groundwater, as well as the atmosphere.

21. Fresh Water • A river system is a network of streams and rivers that drains an area. Also, it contains all the land being drained. • Tributaries are smaller rivers that feed into large, central rivers.

22. Groundwater • Sometimes, runoff infiltrates the ground and collects as groundwater. • Aquifers are rock layers that are porous. They allow for water flow, and even store water.

23. Groundwater • The surface at the entry of an aquifer is called a recharge zone. • Aquifers are found under most of the continental U.S.

24. Exit Ticket • There are two types of ocean currents. Name them. • ________ currents can be classified as warm- or cold-water. • ______-water currents moderate local temperatures. • What do we call small rivers that feed into bigger, central rivers? • ______ are layers of porous rock that allow for water flow and storage.

25. The Biosphere • The biosphere is the narrow portion of Earth capable of supporting life. • It contains the outermost geosphere, most of the hydrosphere, and the innermost atmosphere.

26. The Biosphere • Recall from Chapter 1 that we discussed Earth as a closed system – one that could not gain or lose matter. • However, closed systems CAN gain and lose energy. The sun provides energy to plants and other producers. As organisms are consumed, energy is transferred to the consumer. • In the process, much energy is lost as heat, which is lost to space.