The Hydrosphere and Biosphere Why is water so

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

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

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.

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.

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.

The Water Cycle • Finally, precipitation becomes runoff, and may either: 1. Collect in freshwater storage (lakes, ponds, etc. ) 2. Becomes groundwater 3. Returns to the ocean

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.

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.

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?

Earth’s Oceans • The ocean can be divided into three areas based on relative temperature. 1. Surface zone 2. Thermocline 3. Deep water

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

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.

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.

Exit Ticket 1. Name all four types of precipitation. 2. Most of the water vapor in clouds came from the _____. 3. Runoff (fallen precipitation) ends up in three possible places. Name them. 4. In which layer of the ocean does temperature drop the fastest? 5. How does the ocean moderate Earth’s temperature?

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 winddriven.

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

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.

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.

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.

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.

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.

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.

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

Exit Ticket 1. There are two types of ocean currents. Name them. 2. ____ currents can be classified as warmor cold-water. 3. ______-water currents moderate local temperatures. 4. What do we call small rivers that feed into bigger, central rivers? 5. ______ are layers of porous rock that allow for water flow and storage.

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.

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.