introduction to environment edited

8/14/2019 Introduction to Environment Edited

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Concept Map of the Environment


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Major Environmental Components The lithosphere is the layer of land that forms Earth's surface. The lithosphere includes

the rocks, soil, and sand that make up land:

The hydrosphere includes all the parts of Earth that are made up of water. Thehydrosphere includes oceans, lakes, and rivers, as well as underground water andclouds in the air.

What characteristics make it possible for life to exist in so many parts of Earth? One ofthe most important reasons Earth can support life is the presence of liquid water.Although water exists elsewhere in the solar system, it is usually in the form of ice orvapor. On Earth, liquid water in the hydrosphere stores heat. Water is also found in the

bodies of organisms. Many of the substances that all living things need dissolve inwater. Chemical reactions that take place within organisms occur in water.

The atmosphere isthe layer of air that surrounds Earth.

The atmosphere is an envelope of gases that surrounds Earth and includes the air youbreathe. Scientists divide the atmosphere into four layers. Starting from the Earth'ssurface, these layers are the troposphere, stratosphere, mesosphere, andthermosphere. Gases become less dense the farther they are from Earth's surface.

TheBiosphere

Scientists spend much time trying to understand how the different parts of Earthinteract with each other and with the planet's living organisms. These interactionsamong nonliving and living parts of the Earth are the subject of ecology. The word

ecology comes from the Greek word oikos, meaning home. Ecology is the study ofEarth, the home of living organisms.


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Earths Land The Lithosphere

The lithosphere varies in thickness from about 10 to 200 kilometers (km).Three main types of rocks make up the lithosphere: igneous rock, sedimentary

rock, and metamorphic rock. The rocks are classified on the basis of how theywere formed.

Igneous Rock Below the hard, solid lithosphere, Earth's interior contains hot,melted rocks in liquid form. When liquid rock cools, it solidifies to becomeigneous rock. The lava that flows from a volcano cools and turns into igneous

rock. Granite and basalt are two common types of igneous rock.

Sedimentary Rock Rocks break down slowly over time. The tiny pieces of rockthat wear off become sediments that are carried away by wind and water.These sediments eventually settle down into layers.As layers of sedimentsaccumulate, they become compressed and cemented into sedimentary rock.

Fossils are almost always found in sedimentary rock. Limestone and sandstoneare examples of sedimentary rock.

Metamorphic Rock Pressure and heat deep in the lithosphere can causeigneous and sedimentary rocks to undergo changes in structure. Rock that hasbeen transformed by heat and pressure is called metamorphic rock. Marble

and slate are familiar examples of metamorphic rock.


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The Atmosphere The atmosphere is an envelope of gases that surrounds Earth and includes

the air you breathe. The atmosphere is made up of about 78 percentnitrogen and 21 percent oxygen. Water vapor, dust particles, and smallamounts of other gases make up the remaining 1 percent of the air. Only

about 0.04 percent of the air is made up of carbon dioxide.

Carbon dioxide is a gas that is very important to life on Earth. Carbondioxide is one of the ingredients used by plants to make food. In thisprocess, plants add oxygen to the atmosphere. In the process ofphotosynthesis, plants, algae, and certain bacteria make sugars by

combining carbon dioxide (CO2), water, and energy from the sun.

Animals and other organisms, including plants, break down these sugars,releasing CO2, water, and energy. In humans, much of the energy is used tomaintain body functions.

Carbon dioxide is also released into the atmosphere by volcanic eruptionsand whenever fuels such as wood, coal, and gasoline are burned. Carbondioxide in the atmosphere lets sunlight in and traps the resulting heat. Thisis called the "greenhouse effect." Scientists are concerned that increasingamounts of carbon dioxide in the atmosphere are causing Earth to becomewarmer and changing climate patterns.


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Scientists divide the atmosphere into four

layers, as shown in Figure. Starting from the Earth's surface, these layers

are:

troposphere,

stratosphere,

mesosphere, and

thermosphere. Gases become less dense the farther they are

from Earth's surface.


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Troposphere

The layer of the atmosphere that touches the

surface of Earth is called the Troposphere

The troposphere extends to a height of about 8to 18 km above Earth's surface. Most of the gas

molecules in the atmosphere are in thetroposphere. The troposphere contains most ofthe water vapor in the atmosphere and is thelayer in which most weather occurs.

The winds that carry weather across Earth are animportant factor in the climate of an area.


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Stratosphere

Stratosphere is beyond the troposphere, reaching a height of 50 kmabove Earth.

Weather disturbances that are common in the troposphere do notoccur in the stratosphere.

The upper stratosphere contains a layer of gas called ozone. Ozone is

a form of oxygen gas containing three oxygen atoms per molecule.

The oxygen you breathe in the troposphere contains only two oxygenatoms in each molecule.

The ozone layer is very important to living things because it filters outmost of the ultraviolet, or UV, radiation given off by the sun.

Ultraviolet radiation is one of many types of electromagnetic wavesproduced by the sun. without the filtering action of the ozone layer,

the sun's UV radiation would destroy much of the life on Earth.


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Mesosphere and Thermosphere

Beyond the stratosphere is the mesosphere, which extends up to 85km above Earth's surface. The mesosphere is the coldest layer ofthe atmosphere, with temperatures as low as -100 C.

The thermosphereis the outermost layer of the atmosphere. Unlikethe mesosphere, the thermosphere experiences temperatures ashigh as 2000 C, though air pressure is less than one ten-thousandth of that at Earth's surface.

Gas molecules in one layer of the thermosphere are bombardedwith rays from the sun. These rays cause the gas molecules to loseelectrons, and they become ions.

Because of these ions, this layer of the thermosphere is called theionosphere.

When gas molecules reunite with free electrons, light is given off.This process occurs most often near Earth's poles, resulting in adisplay of lights called an aurora.


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The Biosphere

Earth is home to trillions of organisms. Together, the parts of thelithosphere, hydrosphere, and atmosphere where life exists make up thebiosphere.

The biosphereis all the parts of Earth that support and contain life. Thebiosphere reaches from the floor of the ocean to the tops of the highestmountains.

All together, the biosphere is a layer blanketing the Earth about 20 kmthick. Although the biosphere is 20 km thick, most organisms live in anarrower range.

Deep below the surface of the ocean, life is rare because the pressure is sohigh and very little food is available.

Few organisms live atop the tallest mountains because the air pressure istoo low and the temperatures are too cold. Most life on Earth existsbetween 500 m below the surface of the ocean and about 6 km above sealevel.


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All organisms obtain the materials they need to live from thebiosphere.

While each individual organism may live mostly on land, water, or inthe air, all organisms depend on materials from each of these threeareas of Earth.

For example, we live on the lithosphere, but breathe the air of the

atmosphere, and drink the water of the hydrosphere.

A bird may live in the air, it eats food that grows on the ground,which is part of the lithosphere.

The leaves of the tree, absorb CO2from the atmosphere andrelease oxygen and water vapor. The tree absorbs groundwater withits roots and transports the water to the leaves.


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Organisms find the energy they need in many different parts of theenvironment.

Most energy originates from sunlight, which plants use. Animals,

however, obtain most of their energy by eating plants and otheranimals.

Energy constantly flows into the biosphere as sunlight, flowsthrough organisms and the environment, and eventually flows out

of the biosphere as heat and is lost to space.

Because all organisms depend on the biosphere to meet theirneeds, they are affected by changes in the biosphere.

For example, a change in the composition of seawater can affectthe organisms in the ocean.

The eruption of a volcano can affect organisms that live on thesurrounding land.

introduction to environment edited

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