Chapter 3: The Dynamic Earth

Environmental Science ClassMrs. Toner

Essential Question for this Lesson• How is the Earth a system of interacting

components?

www.nasa.gov

Section 1: The Geosphere• http://photos.travelblog.org/Photos/83584/362141/t/3325183-Lava-flow-down-the-volcano-2.jpg• http://4.bp.blogspot.com/_Gyn0-PcXrJY/SpeZc7IviQI/AAAAAAAAAjI/W0W2qhkNx4s/S668/volcanoUPI_468x311.jpg• http://i.treehugger.com/images/2007/10/24/hurricane-jj-001.jpg

The Geosphere (cont.)• What are the conditions that allow us to

survive on a constantly changing planet?

Earth as a System• The Earth consists of four parts that

all interact with each other:–Rock (Geosphere)–Air (Atmosphere)–Water (Hydrosphere)–Living Things (Biosphere)

Earth as a System: The Geosphere• The solid part of the Earth that consists of all

rock, as well as the soil and loose rocks on Earth’s surface is the geosphere.

• Most of the geosphere is located in Earth’s interior.

http://www.isws.illinois.edu/nitro/images/biggraph.jpg

The Geosphere

http://www.salemstate.edu/~lhanson/gls100/image1/Internal_layersUSGS.gif

Earth as a System (cont.)• The atmosphere is the mixture of gasses that

makes up the air we breathe. • Nearly all of these gases are found in the first

30 km above the Earth’s surface.

http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.gif

Earth as a System (cont.)• The hydrosphere makes up all of the water on

or near Earth’s surface.• Much of this water is in the oceans.• Water is also found in the atmosphere, on

land, and in the soil.

http://www.uwsp.edu/geo/faculty/ritter/images/hydrosphere/hydrocyc.jpg

Hydrosphere

Earth as a System (cont.)

http://www.uwsp.edu/geo/faculty/ritter/images/hydrosphere/hydrocyc.jpg

The biosphere is made up of parts of the atmosphere, the geosphere, and the hydrosphere. It is where life exists.

Earth’s Interior

• The Earth is made up of three different compositional layers:– Crust (least dense)

• Earth’s thinnest outer layer, makes up less than 1% of Earth’s mass.

– Mantle (medium density)• Layer beneath the crust, makes up 64% of Earth’s mass.

– Core (most dense)• Earth’s innermost layer, • Made up of hot nickel and iron at the center of the Earth

Structure of the Earth If we consider the physical properties of each

layer of Earth, then Earth can be divided into five physical layers:1. Lithosphere – Earth’s outer layer• Includes the crust and uppermost part of the mantle• It is a cool, rigid layer• 15-300 Km thick• It is divided into huge pieces called tectonic plates.

2. Asthenosphere – Layer beneath the lithosphere• A plastic , solid layer of the mantle made of rock that

flows very slowly to allow the tectonic plates to move on top of it.

Structure of Earth (continued)

3. Mesosphere– Beneath the asthenosphere– The lowest part of the mantle

4. Outer Core– A dense liquid layer

5. Inner Core– Dense, solid– Iron and nickel– HOT – 4,000 to 5,000 degrees Celsius!– It is solid because it is under enormous pressure

Compositional Layers Physical Layers

Annenberg Media: Earth Revealed Video

• http://www.learner.org/resources/series78.html?pop=yes&pid=317#

Activity – work individually• On plain white paper• Horizontal orientation• Divide the paper into two sections• On the left side - draw, label and color the

compositional layers of Earth.• On the right side – draw, label, and color the

physical layers of Earth.• List three facts for each layer.• Use page 65 in the text as a reference.• Worth 35 points!

Plate Tectonics• The lithosphere is divided into pieces called tectonic

plates.• These plates glide across the underlying asthenosphere.• The continents are located on tectonic plates.• Major plates:– Pacific Plate– North American Plate– South American Plate– African Plate– Eurasian Plate– Antarctic Plate

Tectonic Plate Map

Plate Tectonic Animations• http://www.classzone.com/books/earth_science/terc/content

/visualizations/es0804/es0804page01.cfm?chapter_no=08

• http://www.pbs.org/wgbh/aso/tryit/tectonics/#

Plate Boundaries

• Plate boundaries are the boundaries between tectonic plates.

• Divergent Boundaries - plates move away from one another (seafloor spreading)

• Convergent Boundaries - plates collide into one another (mountains, volcanoes, earthquakes)

• Transform Boundaries - plates slip past one another (earthquakes like the ones in California at the San Andreas Fault)

SECTION 2: THE ATMOSPHERE

Chapter 3, Pages 71-76

Section 2: The Atmosphere• Earth is surrounded by a mixture of gases known as

the atmosphere. – Nitrogen (N2)– Oxygen (O2)– Carbon Dioxide (C02)

• Earth’s atmosphere changes constantly as these gases are added and removed.– As animals and humans breathe in, oxygen is removed from

the atmosphere. As animals and humans breathe out, carbon dioxide is added.

– Plants absorb carbon dioxide from the atmosphere and release oxygen into the atmosphere during photosynthesis.

Atmospheric Gas ExchangeExample

The Atmosphere (Cont.)• The atmosphere also insulates Earth’s surface.• It keeps Earth at temperatures at which living

things can survive.

Composition of the Atmosphere• 1. Nitrogen = 78% of the atmosphere– It enters the atmosphere when volcanoes erupt,

and when dead plants and animals decay.• 2. Oxygen = 21%– Is primarily produced by plants.

• 3. Other Gases = 1%• Methane• Carbon dioxide• Argon• Water vapor

Air Pressure• Earth’s atmosphere is pulled towards Earth’s surface

by gravity.• As a result of gravity, the atmosphere is denser at

Earth’s surface.• The air becomes less dense as elevation increases, so

breathing at higher elevations is more difficult.

Layers of the Atmosphere• 1. The Troposphere :– Extends to about 18 Km (10 miles) above Earth’s

surface– It’s where we live and where weather occurs.– Densest layer of atmosphere– Temperature decreases as altitude increases in the

troposphere.

2. The Stratosphere

• Above the troposphere • Extends 18-50 Km (or 10-30 miles) above

Earth’s surface)• Where airplanes fly• Where ozone layer is• Temperature increases as altitude increases

because ozone in the stratosphere absorbs the Sun’s UV energy and warms the air.

3. The Mesosphere

• The layer above the stratosphere.• Extends to an altitude of about 80 Km (48

miles).• The coldest layer of the atmosphere (- 60 to

- 90 degrees Celsius).

4. The Thermosphere

• Atmospheric layer farthest from Earth’s surface.

• The air is very thin in this layer so it is the least dense of all the layers.

• Nitrogen and oxygen atoms absorb x-rays and gamma rays emitted from the Sun making them electrically charged. This causes the Northern Lights over the North and South Poles.

The Northern Lights

More Northern Lights

CBS Video: “To the Edge of Earth and Back”

• http://www.cbsnews.com/video/watch/?id=5722794n

Energy in the Atmosphere

• Energy from the Sun is transferred in Earth’s atmosphere by three mechanisms:– 1. Radiation– 2. Convection– 3. Conduction

1. Radiation

• Radiation is the transfer of energy across space and in the atmosphere.

• When you stand before a fire, the heat you feel has reached you by radiation.

• See diagram on next slide.

2. Conduction

• Conduction is the flow of heat from a warmer object to a colder object when the objects are placed in direct physical contact.

• Like when you touch the handle of a hot pot.

3. Convection• Convection is the transfer of heat by air

currents.– Hot air rises and cold air sinks.– If you were to hold your hand above a hot iron,

you would feel the heat because a current of hot air rises up to your hand.

– See diagram on next slide.

Energy Transfer Interactive

• http://www.wisc-online.com/Objects/ViewObject.aspx?ID=SCE304

The Greenhouse Effect• Is the process in which gases trap heat near the

Earth. • 1. Sunlight that penetrates Earth’s atmosphere

heats the surface of the Earth.• 2. Earth’s surface radiates heat back to the

atmosphere where some of the heat escapes back into space.

• 3. The remainder of the heat is absorbed by greenhouse gases (carbon dioxide and water vapor), which warms the air and the surface of the Earth.