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 3 rd 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, 2/3 rd 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, 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 ZonesStructural 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? 1 st law of thermodynamics –Energy is transferred between systems, cannot be created nor destroyed 2 nd 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 CycleNitrogen Cycle

Water CyclePhosphorus 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