Ch 2-Earth as a System Objectives –Describe size and shape of Earth –Describe layers of...

Ch 2-Earth as a System

• Objectives– Describe size and shape of Earth– Describe layers of Earth’s interior– Identify possible source of Earth’s magnetic field– Summarize Newton’s law of gravitation– List characteristics of Earth’s 4 major spheres– Identify main sources of energy on Earth– Identify the 4 cycles of matter and energy– Identify the factors that control balance of ecosystem– Summarize how energy is transferred through

ecosystem– Describe how ecosystems respond to environmental

change

Characteristics of Earth

• Only planet w/ liquid water on surface and w/ oxygen in atmosphere

• 3rd planet from sun, 4.6 billion yrs old, made mostly of rock

• Oblate spheroid-slightly flattened sphere

• Pole to pole circumference=40,007 km. Equatorial circumference=40,074 km

Compositional and structural layers of Earth’s interior

• How many compositional zones are there? How many major structural zones are there?– How do scientists know this?– Seismic waves-vibrations that travel through

Earth

• Compositional – Crust-thin, solid outermost zone of Earth, 1%

of Earth’s mass• Continental and oceanic crust

• Mantle-beneath crust, 2,900 km thick, 2/3rd of Earth’s mass

• Core-center of Earth, sphere w/ radius of 3500 km, composed mainly of iron and nickel

• Structural zones– Lithosphere-uppermost part of mantle and crust, cool

and brittle– Asthenosphere-less rigid layer, 200-250 km thick,

solid rock has ability to flow-plasticity– Mesosphere-solid mantle rock– Outer core-dense liquid– Inner core-dense, rigid solid, core makes up 1/3 of

Earth’s mass

Earth’s Interior

Compositional Zones Structural Zones

Earth’s magnetic field

• Earth has 2 magnetic poles, North geomagnetic pole and south, magnetic field believed to be liquid iron in outer core– Motions produce electric currents that create

Earth’s magnetic field

• Sun and moon have magnetic field, no iron or liquid outer core

Newton’s Law of Gravitation

• Earth is affected by gravity-force of attraction that exists between

• Who discovered law of gravitation?

• The larger the masses of 2 obj and closer together the obj are, the greater the force of gravity between the obj will be

Sec 2: Energy in Earth System

• Matter-anything that has mass, takes up space• What are subatomic particles?

– Protons, electrons, neutrons, atoms or molecules

• How can energy be transferred?– Heat, light, vibrations, electromagnetic waves

• Closed system- system in which energy but not matter is exchanged with the surroundings

• Open System- system in which both energy and matter are exchanged with the surroundings

Characteristics of Earth’s major spheres

• Hydrosphere-97% water is salty, 3% freshwater– Where do we find freshwater?– All water except atmosphere

• Atmosphere-blanket of gases that surrounds earth’s surface. Provides air and protects against rays. – What makes up the atmosphere?

• Geosphere-mostly solid part of Earth, rock and soil on continents and ocean

• Biosphere-composed of all of the forms of life in geosphere, hydrosphere, atmosphere– Contains any organic

matter not decomposed

Main sources of energy

• Internal source-used to be radioactive decay, hot materials move toward surface, cooler denser materials sink– Convection

• External source-sun, solar radiation– What does solar radiation cause?

• 1st law of thermodynamics– Energy is transferred between systems, cannot be

created nor destroyed

• 2nd law of thermodynamics– When energy is transferred, matter becomes less

organized w/ time, energy is spread out over time• How is matter and energy exchanged?

Processes in which matter and energy cycle on Earth

• Nitrogen cycle

• Carbon cycle

• Phosphorus cycle

• Water cycle

• All natural cycles can be altered by human activities. Give examples

Carbon Cycle Nitrogen Cycle

Water Cycle Phosphorus Cycle

Sec 3-Ecology

• What is ecology?– Study of relationships between living things

and non living things in environment

• What is an ecosystem?– Community of organisms and the environment

that the organisms inhabit

• What do you find in an ecosystem?

What factors control the balance of an ecosystem

• Carrying capacity-largest population that an environment can support at any given time

• What is earth’s? What happens if something happens to something in ecosystem?

• What is ultimate source of energy?

Energy transferred through ecosystem

• Energy is continually being exchange through different processes.– Producers, consumers, sec consumers

• Food Chain-organisms eat more than one specie. Food web-used to represent relationships between multiple food chains

How ecosystems respond to environmental change

• Overconsumption of resources

• Converting large natural areas to agriculture or urban areas

• Pollution