1- Chapter THE EARTH SYSTEM
4 levels of earth system:
1) Hydrosphere- earths water, includes oceans, lakes, rivers, ponds, streams, ice and snow. Excludes water vapor in the atmosphere 2) Atmosphere- mixture of gasses such as nitrogen, oxygen, carbon, argon, co2, and water vapor. It surrounds the earth 3) Biosphere- life on earth. Earths organism as well as organic matter (that's not decomposed) 4) Geosphere- solid earth. Consists mostly of rock and regolith (blanket of loose rock particles on the earth's surface) Scientific Method the use of evidence that can be seen and tested by anyone with the resources needed to do so a) Observation- Acquiring the evidence, measured and observed b) Forming Hypothesis- explaining their observations as an explanation for the way things happen. c) Testing the Hypothesis and formation of theory- testing your observations and hypothesis. More factual than opinionative d) Formation of a Law- scientific law. Multiple theories thrown into one law. Clear statement about the theories. e) Continual reexamination- not all laws are 100% proven. Many new theories can still be developed about an existing law. Its like needing to recheck your work
The System Concept A SYSTEM is a smaller portion of the universe that can be isolated from the rest of the universe for the purpose of study, observation, and noticing changes. - Since its isolated, must have some kind of boundary with its surroundings - Types of Systems: A) Isolated System: completely closed off. Prevents exchange of matter and energy with its surroundings. No perfect boundary, so not 100% blockage. B) Closed System: boundary that permits energy exchange. No matter contact with the system C) Open System- can exchange both matter and energy across boundary. Experiencing the full amounts of change New Science and New Tools Remote Sensing- Observation on very large scale for extreme details that aren't normally measured. Ex. Satellite observation and deep water submarines Geographical Information Systems (GIS)- used with remote sensing to show picture of certain geographical conditions on the earth and other planets. -
Living in a Closed System: - Earth is a closed system - External source of energy a) Amount of matter in closed system is finite a. Not unlimited resources on earth b. Waste material must stay within the system b) When changes are made to one part of system, others may be affected a. Connecting outcomes b. Ex. If I light a fire in the forest, the trees would burn down, which means that the animals in the forest will have to find a new home, which means that the nearby forests will be overcrowded, which means that there might be a shortage of food or too much food, which means that certain populations of animals in certain areas might become lower/higher. Box Models Shows the storage and movement of materials and energy Interacting systems Reservoir- a storage tank, mostly for water Residence Time- The amount of time that water stays in a reservoir
INTERACTIONS AMONG SYSTEMS Feedback- when the output of the system also serves as an input and leads to changes in the state of the system 2 types of feedback: a) Negative Feedback: systems output is in the opposite direction of the input. Ex) House Heating system: house cools, thermostat closes, when furnace is on, house warms, thermostat open, change in temperature. b) Positive Feedback: increase in leads output to a further increase in the output. Ex) fire in a forest Cycles and Flows 4 cycles: Energy, hydrolic, biogeochemical, and rock a) Energy Cycle- external and internal energy sources. Must be an overall balance between energy interaction, storage, and addition/subtraction. Laws of Thermodynamics:
a) First Law: in a system of constant mass, the energy involved in any physical or chemical change is neither created or destroyed, but changed from one form to another. b) Second law: energy always changers from a more useful, more concentrated from to a less useful, less concentrated form. c) Entropy- measure of disorganization of energy. Measurement of the dispersing of energy by heat and increased energy reactions. Geothermal Energy- the Earths internal heat energy. Second to most powerful source of energy. That energy always finds its way to the surface. Ex. Volcanic pathways Tidal Energy- Smallest energy source on earth. The interactions of tides in the ocean. "tidal bulge"
Energy Loss
2 ways to lose energy: a) Reflection: about 40% of energy that goes into the earth is reflected back into space. The percentage reflected can be called albedo. b) Degradation and Reradiation- The rest of the energy that isn't reflected is absorbed by materials at the surface of the earth, specifically the atmosphere and hydrosphere. Energy converted to different forms. Hydrologic Cycle - The fluxes of water between the various reservoirs of the hydrosphere. a) Evaporation- water vapor formed from heat energy, builds up and may cause precipitation (Rain/snow) b) Condensation- formation of clouds after evaporation - Rain may be evaporated, or may drain off to become Surface Runoff. - Some of the water goes into soil - Some also becomes ground water, in some vast underground water reservoir Ocean: Largest reservoir- contains 97.5 % of the water on earth. The rest is Freshwater reservoirs. Nitrogen Cycle: an example of a biogeochemical cycle Describes the movement of a chem. Element or compound among bio/geological systems. Nitrogen is removed from the atmosphere or made accessible to the biosphere by: o Solution of N2 in the ocean o Oxidation of n2 by lightning discharges to create NO3, which is rained out of the atmosphere and ends up in the soil/ocean. o Reduction of N2 to NH3 through nitrogen-fixing bacteria in the soil or sea
The Rock Cycle and Uniformitarianism
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Catastrophism: A catastrophe that is so huge that it cannot be explained (ex. The beginning of earth or things that happened in the bible) Weathering- the complex group of related processes in by which rock is broken down Erosion- breakdown of products are moved around (ex. Hills, cliff rocks) Principle of Uniformitarianism- states that natural laws do not change and therefore the processes that we see in action today have been operating the same way throughout the earth's history. (Ex. A sand dunes structure)
The Biological Dimension Three features that make the Earth unique: 1) 2) 3) Plate Tectonics- The continual arrangements of the continents and oceans Liquid water Life Free Oxygen in the Earth's atmosphere is the result of 3 billion years of photosynthesis and is therefore a product of life
The Human Impact: Global Change: Changes to the earth system as a result of human activity May not necessarily be negative: positive global changes due to certain human activities