PHYSICAL GEOGRAPHY GEOG 1401
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Tracy Gusikowski I
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This 26 page Class Notes was uploaded by Tracy Gusikowski I on Thursday October 22, 2015. The Class Notes belongs to GEOG 1401 at Texas Tech University taught by Jeffrey Alan Lee in Fall. Since its upload, it has received 28 views. For similar materials see /class/226365/geog-1401-texas-tech-university in Geography at Texas Tech University.
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Physical Geography TEST 3 REVEIW From The Scienti c Endeavor Communism 0 scientific knowledge is the property of everyone 0 not always practiced military commercial Universalism there are no privileged sources of scientific knowledge 0 scientists nationality gender race religion political persuasion should have no effect on how work is judged Disinterestedness 0 lack of bias or a lack of selfinterest 0 expected to pursue their work mainly for the advancement of knowledge not for personal gain or to advance a political cause Originality 0 Scientific work should advance knowledge 0 work that provides nothing new to our understanding is not regarded highly Skepticism 0 it is the duty of the community of scientists to judge scientific work carefully and critically and to reject work that lacks merit 0 institutionalized in the form of peer review Invisible colleges communication networks that transcend national borders and have formal and informal components Peer Review members of invisible colleges are involved in the evaluation of each other39s work Fraud 0 Fabrication making up information used to justify a result or making up the result itself 0 Falsification data or results are changed inappropriately such as improperly deleting data that do not support one39s expected results Plagiarism the use of someone else39s words or ideas without giving proper credit Conflict of Interest if a scientist is concerned with both the advancement of knowledge and the making of money one would have to be compromised Rocks and Weathering Mineral naturally occurring inorganic compound with a characteristic crystal structure Example quartz Igneous Rocks formed by cooling of magma molten rock make up 95 of earth39s crust 39 Intrusive solidifies below the surface extrusive cools at surface Sedimentary Roc s form when material accumulates in an area and is turned into a rock 39 Clastic made of particles of broken rock or remains of organisms Categorized by size 0 shale clay mudstone mixed silt and clay siltstone silt sandstone sand conglomerate pebbles and larger 0 limestone made up of skeletons of marine organisms and size does not matter 39 Chemical form when material that was chemically dissolved in water settles out 0 if more of a substance exists in seawater than the water can hold some will precipitate out and collect at the bottom 0 o o o 0 in arid areas evaporating water can leave salt deposits known as evaporites I Organic made of formerly living things Metamorphic Rocks when a rock is altered by heat and pressure 0 k I I I r r 0 contact metamorphism rock is changed by contact with magma Rock Cycle Igneous Magma Sedimentary Metamorphic Weathering I I I I 4 4 I saliva I J r Depends on several factors I 39 quot h easily 39 39 39 439 IIIiIIeIaI I availability of water water helps dissolve minerals I temperature chemical reactions work faster at higher temperatures 39 availability of 39 39 39 t can L quotquot quot quot 0 Solution where minerals are dissolved by acidic water 0 u I I I I I I u I I 1 1 the minerals 0 Oxidation where iron and aluminum compounds are modi ed 0 Parent matter natural resistance to weathering and is left behind I J 39 39 quot is broken 39 39 quotquot 39 piece I 0 internal expansion most common in intrusive igneous rocks that solidi ed at temperatures and pressures different from those at the surface So when they are exposed at the surface they quotW h the quot 39 rock llake offquot L o F r water I y r I I I 0 Salt c s grow in deserts when salty water evaporates leaving the salts behind rystal Relation Between Chemical and Physical Weathering r Chemical weathering depends on the amount of surface area available to be attacked Physical weathering makes more surface area So therefore physical weathering should increase the rate of chemical weathering lfwe go back to the candy ana o alter the teeth break the suc 39 smaller pieces there is more surface area for the saliva to work on so the sucker disappears faster Hydrology Hyrologic cycle 8 mp Sm Moiszuw OLEan I run yumme ion when water gets caught in vegetation In ltration when water goes into groun puddles what doesn39t in ltrate runoff water owing over surface Evaporation r k r 39 39 quot meail evaporation Warmer water evaporates faster than cooler water lfair quot 39 quot henthere39 r mum formoreWate apm 39 39 ll ail 39 39 rum 39 39 k L 39 forthe evaporating water Transpiration r uuuugn luul 39 39 me surface of the plant39s leaves Porosity amount of space between particles Permeability ease with which water can flow through a soil Law Pumsny Luw Pevmeammy e g sm Htgh Pumsny Law Peimeahthly e g may Htgh Pumsny Htgh Pevmeabhly e g sand Law Pumsny Htgh Peimeahthly e g cracked smt Factors that effect in ltration vege a Ion soil animals gophers and prairie dogs loosen soil large animals walk on ground and compact soil intensity of rainfall Soil Moisture u 39 39 39 39 some on me vvaicl 39 r the soil toward groundwater Some ofthe water though will be kept in the soil attached to the soil particles Capillarywater water molecules attached to soil particles Gravity water The farther away from a soil particle the weakerthe attraction so eventually gravity is stronger and carries the rest ofthe water downward Field capacity amount ofwater left in the soil after it has drained wilting point state of soil if plants cannot get enough water to stay healthy Groundwa r As gravity water ows down 39 39 39 r r me material amuum u gluulluwaiel 39 39 r where the water is found usually sediments or rock aquifer If k quot 39 39 39 quot r roundwater aquiclude If k 39 quot u um water 5 39 39 water table upper limit of groundwater u n satu rated water table 1 surface gloundwater aquufer aquitlude artesian well ows by itself because the water is under pressure the well top is lower than the water table cone of depression forms when a well is dug and water is pumped out 1 can lower the water table under neighboring wells which can leave shallower wells dry Runoff 39 Overland ow water that is owing over the entire surface 39 Through ow If gravity water is slowed by decreasing permeability with depth often at the top of the B layer it is de ected and ows downhill through the soil and emerges at a lower point on the hill mm v overland flow 39 ll39l oughfiow l vaert ge baseflow Base ow When the water table is higher than the bed of a stream the groundwater will feed the m 0 the stream is said to be ef uent 0 Perennial streams baseflow is what keeps streams flowing all year long Ef uent Stream 3 van ei awatertable 4 H k 39 baseflow 39 In uent Streams ln dry areas the water table is o en lower than the bottom of the streams so the streams contribute to groundwa er Influenl Stream Dix 0 ephemeral stream water will only exist in the streams during rainstorms or snowmelt and for a short time after then the stream will be dry stream will be ry 0 Intermittent streams are in between in that they are ef uent for part of the year the wet season and influent for the rest of the year Hydrographs show the relationship between rainfall and stream ow for a given stream Salt water intrusion lnltlal situation 00 leh umplng well we salt quot boundary boundarv Fluvial Geomorphology Geomorphology Lthe study of landforms and the processes that shape them Historical Development John Wesley Powell one of the biggest contributers base level the lowest level an area can be eroded Grove Karl Gilbert L part of a group of earth scientists thatworked with Powell L established g ipn i g Graded river From this energy a limited amount or sediment can be carried stream energy is based on he amount orwaterrlowing in the stream and the slope orthe channel ltis orthe to it and the amount of water in the stream moresedlmentlhan energyto u movellisosomedeposlted slope Increases amp energy increases lessseormentthan available energy m lo move IL so some eroded llom bedL slope decreases I less energy Vl lliam Morris Davis L yiewed landforms as products of geologic structure the rocks and how they are arranged geomorphic process how material is eroded transported and deposited stage ordeyelopmen L Cycle of Erosion peneplain a rapid uplift a youth a Maturity a OldAge Peneplain rapid uplif Youth W Maturity W Old Age Peneplain Force and Resistance Kinetic energy when an object is moving if the object encounters another object some of that kinetic energy is used force is applied to the other ob39ect Potential energy If an object is located above its surroundings because of its position gravity has the potential to pull it down and convert the potential energy to kinetic energy Any object above base level i Fluvial Processes Discharge Q equals the crosssectional area of the channel A times the average velocity of the water V or QAV water level rossrsecuonal area slowest laminar flow each water molecule travels in a straight line This only occurs at very slow speeds which are found only right next to the stream bed few millimeters turbulent flow where eddies occur and water is moving in all directions but with the net movement Stream velocity is determined by four factors the slope of the channel water flows faster in steeper channels the discharge the more water there is the less overall slowing by friction the shape of the channel shallow water is slowed more than deep water the roughness of the channel If a stream bed is very rough say boulders it will generate a greater amount of friction on the water and slow it down more than if the bed is relatively smooth like sand o 000 positively related ifwhen one changes the other changes in the same way negatively related if an increase in one is associated with a decrease in the other or viceversa Therefore 39 39 39 quot quot39 L 39 re ated to bed Is pu ill euy roughness Stream Energy shear stress the bed of a stream takes some ofthe owing energy ofthe stream U Transportation Water Speed Deposition Particle Size Stream Load 39 material carried by a river is called it39s load Bedload is the larger particles that move along near the bed ofa stream Competence the size ofthe largest particle it can move 39 Capacity the maximum amount of material a stream can carry at a given discharge volum lfthe load is less than the capacity then the stream has excess energy and will erode if possible Erosion 39 hydraulic action erosion of loose materials on the bed that are picked up by the running water and carried aw y 39 bank caving hydraulic action undermines the sides ofa channel which causes landslides of bank material into the moving water 39 Abrasion When rock particles are carried along and smash into other material 39 Corrosion chemical weathering in the stream itself and this too wears away susceptible rocks Deposition quotquot 39 39 stays in me Wale 39 quot quot quot quot ifthe tractive force is lowered suf ciently What makes tractive force decrease J Slope can decrease and thereby slowing the water J water can seep into the bed reducing the discharge u the channel can change shape J the stream can enter standing water 0 increasing amount of sediment thus exceeding the capacity or competence Erosional Landforms waterfall Strong Weak W Depositional Landforms 39 delta when a stream enters a body of standing water like an ocean or lake it loses it39s velocity and so its ability to transport its solid load Alluvial Fans when a stream leaves a mountain canyon and ows onto a plain deposition ofmaterial occurs common near mountains in desert areas Floodplains 39 If a stream has cut a wide valley by lateral erosion it frequently is near its base level and typically deposits a layer of alluvium or streamdeposited sediment on the oor of the val ey 39 stream then ows over alluvium 39 quot quot39 r quot L quot and at 39 on either side ofthe channel stream channel 1 floodplain natural levees lloodplain 39 agradation build up of sediment 39 de radation eroding of a surface Stream Channel Patterns 39 meandering when streams bend braided streams with several channels water ows faster on the outside ofa bend than on the inside because it has to travel farther to get through the bend cut bank erosion occurring on the outside leaves a relatively steep cut bank due to the undercutting of the slope and bank caving on the inside of the bend the deposition leaves a point bar deposit which builds out into the stream braided channels found where there are high sediment loads in the stream and where the discharge varies signi cantly ifthe stream m r A u 1 A ta a m t r it does this by depositing material in bars or mid channel islands Cross Sectlons without bars 9 With bars AAIL MapView Drainage Basins 39 drainage network a system of connected streams 39 quot L 39 h drained L quot 39 IVI s quot 39 39 39 Interior drainage there is no surface outlet for the drainage 39 to a playa an ephemeral or intermittent lake ongitudinal Pro les u 5 Hum 39 commonly you will nd that the stream gradient another stream or mouth This is related to the concept ofthe graded rive or slope decreases r 39 In the downstream direction for many streams the size of sediment particles decreases due to abrasion and other factors and the discharge increases Both chan es lead to lower gradients in the downstream direction Atypical longitudinal pro le is described as concaveup curves have quot 39 r r onvex r r Aeolian Geomorphology Air and water Like running water wind is capable of transporting sediment and so shaping the earth39s surface Air flowing over the ground acts like water owing er the bed ofa stream air in contact with the surface is slo d by friction 39k water in streams the air flows in a turbulent fashion faster 4gt 4 gt slower ground surface Transport Erosion u or m EL 7 39u E Transportauun E Depcsmon Pamcle SlZe Waystotravel C 39 39 r 39 quotH foreddi 39 rukeepthemfromfalling t u I 1 z r C saltation smaller sand grains bounce along nearthe C creep larger sand grains are generally pushed and rolled along the surface sorting Because the wind transports sediment in different ways for different sizes the sediment becomes segregated by size Factors Affecting Vl nd Erosion wind p ed the faster the wind blows the greater the force of the wind exerted on the surface Vegetation if plants or other objects absorb so e ofthe force ofthe wind rather than the soil particles then a higher wind speed will be needed to start transport soil conditions if the soil particles are bound together then the threshold wind speed will be higher C er nd salts are effective at binding soil particles together Sand Dunes Landforms formed by blowing sand C Ripples sma ridges generally less than a few centimeters in height Ergs huge accumulations of sand cover Dunes in between 39 me winu 3939 3939 39 along coasts although dunes can be found in other areas too theArctic for example I angle of repose for loose sand Is 34 n deserts and n wlnd rest backslope sllpface Types of Dunes c m I generally form where one wind direction dominates Crescenth Rldge Transverse Rldge H mm C Linear Dune crests parallel to the wind direction I n r L L Wmd Directlon come 39om two close directions say south and southwest mm dlvectlons during year Unear Dune C Reversing and star dunes found in areas with winds from signi cantly different directions I quot 39 quot 39 39 quot 39 439 39 y m the dune 1 rr will move in one direction part of the year and then migrate back the other part Star quot 39 quot 39 39 ot er the dune will rant onhe ridges L Wind pan 01 year Q Reversan dune W Wind the rest ofthe year Star Dunes A H wInd diieclions parabolic If part of quot 39 quot paIIi IIuI for k k39 kills the nlanl 39 39 39 39 39 39 2 n u Txmel agged a eiongaleu into vegclaled E 30M dune Wm Duecnnn lowout or de ation hollow is a depression formed by removing sand or soil often after vegetation has been remove 39 39 39 uue Iu me presence of vegetation t Blowing Du H Vu r Bagnold is one ofthe most in uential geomorphologists Glacial and Periglacial Geomorphology glacier an accumulation of ice alfected by past or present movement a Ia I Ia Ia k I me snow arm I gIeaIeI melting and sublimation in the summer 39 I ine glaciers glaciers in mountainous areas Glacier Mass Ba ance an accounting system I I 1 a 39 39 ablatIonlce is lost by lting 0 sublimation ice goes from solid to gas 0 evaporation ice melts then goes to gas calving chunks of ice falling into water become icebergs Glacial Erosion plucking frost action takes place under the glacier 0 Water beneath a glacier melts relatively frequently and can seep into cracks in the rock This water then refreezes and expands and breaks off pieces of the bedrock which are carried away by the glacier Scour or abrasion 0 the rocks carried on the bottom ofthe glacier wear away at the bedrock acting like a large piece of sandpaper 0 Like sandpaper if the material doing the scouring is fine scour tends to make the bedrock smooth cirques At the upper end of an alpine glacier plucking is very effective so that the bedrock is eroded back This results in an amphitheatershaped depression with an opening where the glacier flowed out arete where two cirques meet with a glacier on either side the ridge becomes jagged horn lfthree cirques meet a peak is formed that is also jagged hanging valleys The ice flowing in a tributary valley simply gets dumped on the ice in the main valley When the ice retreats and streams flow where the glaciers did the tributaries enter the main valley somewhere up on the wall Sediment Transport by Glaciers lateral moraines sediment from the side slopes is carried along the sides of the glacier medial moraine when two glaciers merge Continental glaciers drumlins Groups of low hills kettles a chunk of ice stagnates while the rest of the glacier retreats it can be surrounded by sediment so that when it does melt it leaves a hole erratics boulders that were transported by glaciers and deposited far from their bedrock sources 0 O O Periglacial Geomorphology cold environments that are not continuously covered with ice permafrost permanently frozen soil patterned ground the rocks in the soil are sorted and arranged 0 reason these patterns arise is still somewhat of a mystery but an important component is the way in which different sized particles respond to frost heaving Larger particles do not come back down as far as small ones when the water melts and over time the large stones accumulate along lines o GEOG 1401 Dr Jeff Lee Exam 2 This homework is not collected but serves as a study guide for each exam You should keep pace with the lectures in doing these except for The Scienti c Endeavorand Map Locations which can be done at anytime This should be done in addition to general reading of the chapters and reviewing the lecture notes Answer the following endofchapter questions from Geosystems Chapter 4 Questions 912 2123 Chapter 5 Questions 13 78 10 13 1829 Chapter 7 Questions 1 6 1115 Chapter 16 Questions 12 1116 1819 Chapter 8 Questions 1723 Explain the following concepts in The Scientific Endeavor Chapter 3 Hypothesis generation by analogy induction deduction intuition Serendipity Independent amp dependent variables Cause and effect Sample Control group hard amp soft sciences Experimental bias sampling subject amp experimenter Double blind studies Experimental protocol Type amp Type II errors Post hoc hypothesis Hardware amp software models Terms and Concepts to Know from the Lectures Winds Global amp Local Global variation in net radiation Onecell model Coriolis effect Threecell model Hadley Cell Subtropical High ITCZ Ferrel Cell Subpolar Low Polar Cell Polar High Polar Easterlies Westerlies Trade Winds NE amp SE Horse Latitudes Direction and temperature of ocean currents Gulf Stream Specific Heat Land amp sea breezes Monsoons Valley amp mountain breezes Atmospheric Moisture Evaporation Condensation Sublimation Absolute humidity Relative humidity Dew point Ways to achieve condensation Diabatic processes Dew Radiation fog Advection fog Adiabatic processes Dry adiabatic lapse rate Wet adiabatic lapse rate Condensation nuclei Stratus Cirrus Cumulus Nimbus Forms of precipitation Atmospheric stability Convectional precipitation Orographic precipitation Rainshadow effect Mid Latitude amp Tropical Weather Systems Air masses cP cT mP mT cold front warm front occluded front Dryline Cyclone amp anticyclone Polar Front Rossby Waves Polar Jet Stream Cyclogenesis Mid latitude cyclone Thunderstorms Tornadoes Hurricane formation Global Climates Koppen System A climate types B climate types C climate types D climate types E climate types H climates Continentality Global Climate Change El Nino Milankovitch Cycles Eccentricity of orbit Precession of equinoxes Obliquity of axis Global Warming Greenhouse gasses Temperature record Medieval Optimum Little Ice Age Warming trend now Testing models Consensus of opinion of experts Geoengineering Biogeography Evolution Natural Selection Micromacro evolution Darwin Species Range Dispersal Adaptation Abiotic factors Biotic factors Limiting factor Ecology Ecosystem Energy flow Biogeochemical cycles Biodiversity Introduced species Plate Tectonics Orders of Relief 2nd Order Features of Oceans 251 Order Features of Continents Wegener Paleomagnetism Sea Floor Spreading Convection Cells in Asthenosphere Plate Boundaries Divergent Transform Faults OceanContinent Convergent ContinentCont Convergent OceanOcean Convergent Pangea Laurasia Gondwanaland Terranes MAP LOCATIONS Be able to find the following locations on a map Use the blank world map in the Lab Manual MAJOR RAINFORESTS Amazon Basin look for Amazon River Congo Zaire Basin look for Congo River Indonesia look for the island MAJOR DESEBTS Use Goode s World Atlas in Lab Boom North America Mojave Sonoran see state of Sonora and extending into US Chihuahuan see state of Chihuahua and extending into US Great Basin South America Atacama Africa Sahara Kalahari Namib Middle East Bub al Khali Sinai see Sinai Penn Asia Great Indian AKA Thar Takla Makan Gobi Australia Great Sandy Great Victoria Gibson Simpson 92109 Physical Geography Test 1 Review Science the acquisition of reliable but not infallible knowledge ofthe real world including explanations ofthe phenomena a way of learning about things rocess we use to improve our understanding ofthe universe and all that is in it Measurable Phenomena Research 39 Basic driven by curiosity of the scientist who simply wants to learn more about particular phenomenon 39 Applied done to solve a specific problem and often leads to new or improved technology Scientific Statements attempts to describe or explain real phenomena Scientific Methods 39 Empiricism reason alone is not sufficient ideas must be tested in the real world thus making observation measurement and experiment central aspects of science 0 Induction scientist goes out and measure aspects of the phenomenon under study 0 Deduction start with a theory then move on to data collection and then analysis 39 Positivism starts with a scientist thinking about the phenomenon he or she plans to study 0 Hypothesis based on what the scientist thinks is the likely situation and may come from observations by the scientist the findings of other scientists or simply hunches Theory a hypothesis that has passed a test but has not been proven as law L w when most scientists in a particular discipline are convinced that a hypothesis will pass every conceivable test 39 Falsification scientists make a hypothesis and then try to show that it is not correct 0 0 Scientific Knowledge 39 Textbook information found in wellestablished knowledge and is considered highly reliable by most scientists 39 Frontier cutting edge research where hypotheses have not been tested sufficiently to warrant the trust put in textbooks Objectivity evidence from the real world determines if a theory is correct and the prejudices of the scientist do not effect the results presented Subjectivity scientists are people and have their bias Science is said to be theoryladen in that theories strongly influence how science is done Regional Geography regional geography seeks to explain why certain areas are clearly distinct from other areas Regional geographers try to explain this by combining the cultural historical and physical features of the areas In practice it is fairly easy to describe areas and speculate why they are so but it is almost impossible to explain it HumanEnvironment lnteractions Geographers have also concentrated on the relationships between people and the environment how do they affect each other Scholars now are taking a more reasonable we assume approach by showing that the environment does affect culture but is only one of many influences Spatial Science Many geographers now concentrate on explaining why things vary over the face of the earth This area has been big since the 196039s There is a focus on the processes that cause things to be different from one place to another For example human geographers ask why towns are spaced the way they are Physical geographers ask what causes the climate to vary or why do streams act differently in different areas environmental determinism culture is largely a product of where a people live Systems system a structured set of components which are related to each other and which operate together as a complex whole Types 39 Open systems most common Energy and materials pass through the system 0 ex human body food passes through 39 Closed systems energy passes through but not materials 0 ex the earth it receives energy from the sun it gives off energy to space but there is no material entering or leaving the system 39 Isolated systems no exchange of energy or materials 0 The universe presumably is an isolated system but no other natural isolated systems exist equilibrium no change will occur in the system unless there is a change in the energy steady state equilibrium if the average stays the same dynamic equilibrium If the system fluctuates about a changing mean Thresholds Sometimes systems can change drastically from a small change in the amount of energy input Feedback change in one component of a system brings about a change in another component which in turn brings about a change in the first 39 negative feedback the system is selfregulating 39 positive feedback the system goes out of control Sometimes systems don39t respond to changing situations immediately Delays in system changes are called lags System resilience refers to the way in which a system reacts to a change Origins Atoms are the building blocks of matter and they are made up of protons with positive electrical charge neutrons with no charge and electrons with negative charge Elements are determined by the number of protons Molecules atoms held together 39 plasma When matter is hot enough for the electrons to be separated from the nuclei stars Nuclear Fission nuclear power break up nucleus and protons to make new element Nuclear fusion merge nuclei together form another element solar energy Forces Electromagnetic 0 things either have a positive or a negative charge or they are neutral with no electrical charge 0 positive and negative are attracted to each other same charge repel version of electrical force Electromagnetic force is primarily involved in holding atoms and molecules together Strong and Weak 0 work within nucleus 0 affecting only protons and neutrons 0 While protons are all positively charged they stick together because the strong and weak forces are greater than the electrical force within the nucleus Gravitational 0 any two things are attracted to each other 0 The 0 amount of attraction is determined by how much mass each has and how far apart they are 0 o o 0 Big Bang happened around 14 billion years ago universe was a small ball of energy smaller than a pea A point with no size that was extremely hot billions of degrees when the Big Bang occurred this ball of energy started expanding and cooling 0 first second sub atomic particles formed and the strong and weakforces caused them to merge into protons and neutrons making hydrogen nuclei one proton and deuterium nuclei one proton one neutron Some of these joined together to make helium nuclei 2 protons 2 neutrons 0 not much happened for a few hundred million years except that the expansion continued enough cooling occurred bringing the temperature down to a couple thousand degrees when the EM force came into play and electrons joined the nuclei making atoms 0 hydrogen and some deuterium made up most of the matter with helium almost all the rest 39 All ofthis matter continued to fly away as the universe expanded Some areas had more mass than other areas and these compressed by the action of gravity into galaxy clusters 0 Within these clusters some areas were denser than others and these formed galaxies and within them denser areas formed into stars 39 Stars are dense masses of hydrogen and helium plasma so dense that they heat up Solar System 0 Around 46 billion years ago a bunch of this interstellar dust coalesced and our solar system began to form 0 Most of the matter concentrated in the center forming the sun while some remained separate moving around the sun like a big rotating disk Planet Earth Layers Core 0 mostly iron and nickel and has two parts 0 solid inner core and a liquid outer core Mantle 0 Three parts lower part is solid and makes up most ofthe mantle I asthenosphere which is a soft layer where material can move Above the asthenosphere is another solid layer ofthe mantle Crust 0 Lithosphere upper part of the mantle and the crust lumped together 0 divided into oceanic crust and continental crust I oceanic crust is made of denser rock material with a lot of magnesium and iron I continental crust is less dense and has lots of the minerals quartz and feldspars Formation of oceans early mantle was 20 water water escaped during melting Formation of atmosphere escaped from mantle first atmosphere was made up of nitrogen hydrogen sulfide and carbon dioxide 39 oxygen came later atmosphere is now 78 Nitrogen 21 Oxygen and 1 other Formation of Moon in the early solar system there were many collisions with small planets asteroids etc early on one hit earth 0 core joined with the Earth 0 mantle few off and made moon Development of Life Somehow chemical changes brought about simple amino acids and these changed over time into proteins 0 These somehow developed DNA and RNA and started replicating themselves somehow single celled organisms formed in the oceans by about 38 billion years ago Around 35 billion years ago photosynthesis developed 0 allowed organisms to manufacture their own food 0 added oxygen to the atmosphere which led to ozone O3 in the upper atmosphere Evolution each generation of a species has variation some will be more likely to survive and reproduce 39 natural selection the idea that those better adapted to the environment are more likely to reproduce Radioactive Decay Earth s core is very hot and that heats the mantle and that heat extends to the crust source of this heat is radioactive decay 39 Some elements are found in different forms which we call isotopes some isotopes are unstable in the sense that the nucleus changes over time and one byproduct ofthis change is the release of energy or heat Half Life The time it takes for decay to occur varies with the isotope ex If you have 100 grams of the potassium isotope then 13 billion years later there will only be 50 grams of the potassium isotope left the other 50 grams will be the argon isotope In another 13 billion years it will be reduced to 25 grams of Potassium then 125 grams afteryet another 13 billion years n so on Age of the Earth current estimate is about 46 billion years and this is based on radioactive decay 39 In 1654 James Ussher an Irish archbishop and scholar estimated the year of Creation at 4004 BC mainly by counting the quotbegatsquot in the Old Testament Catostrophism some scholars deviated from the biblical interpretation and felt that the Earth39s surface could be explained by a series of massive floods James Hutton 0 spent much time looking at the rocks near his home 0 on his travels and came to the conclusion that the past could be explained simply by applying the processes working today 0 uniformitarianism Instead of requiring great catastrophes to explain the features of the Earth39s surface Hutton reasoned that the past was pretty much like the present and over time the surface was gradually shaped by things like rivers Charles Lyell 0 close follower of Hutton 0 did the most to convert the world to the uniformitarian view 0 went to the extreme of believing that everything in the past operated exactly as it does today which we now know is too strict an interpretation 0 did not know about things like ice ages until later in his career or that massive floods do occur occasionally Today we generally hold to the uniformitarian view but not too strictly we leave room for occasional catastrophes Energy and Matter Matt er stuff that makes up the universe elements basic types of matter defined by number of protons molecules one ore more atoms bound together ex 02 H2O isotope variation of element different neutrons 0 Carbon is a good example almost all carbon on Earth is Carbon12 with six protons and six neutrons Carbon13 also exists with six protons and seven neutrons Some isotopes are unstable and undergo radioactive decay O O 0 ion atoms or groups of atoms are found with a positive or negative electrical charge 0 cations are positive anions are negative organic compound based on carbon the substances making up living tissue are organic inorganic like most rocks and minerals o ability to do work Kinetic energy is energy being used in motion Potential energy is stored energy that may be used in the future Forms Chemical plants battery electrical created by charged particles heat Vibrating atoms and molecules hit each other and the collisions Electromagnetic radiation a form of energy that is given off by all objects and it travels in waves Wavelength is the distance from the crest of one wave to the crest ofthe next one StephanBolzman Law tells us the amount of energy given off by a body abbreviated here as E 0000 l E o T4 the amount of energy given off by an object is proportional to the temperature raised to the fourth power Wein39s Law says that xpeak cT as temperature goes up the peak wavelength goes down blackbody is a perfect emitter of radiation and does follow above laws Sun and Earth Thermodynamics energy changes 1St law there is a set amount of energy in the universe and that amount never changes 2quotd law no conversion of energy is 100 efficient 0 Entropy is the amount of disorder in a system concentrated energy is more usable total out no usable ener can decrease entropy one place by increasing it somewhere else Units of Measurement The unit of mass is the kilogram A kilogram is the mass of a liter of water The unit of force is the newton named for Sir Isaac The unit of energy is the joule The rate at which energy is given off taken in or transmitted is power and the official unit is the watt Temperature 0 Degrees Celsius based on the temperature at which water freezes and boils 0 Kelvin uses the same increments as C but the starting point is absolute zero the temperature where molecular motion stops EarthSun Relationships Solar Energy Fusion in core releases energy energy gets to surface after 1 millions years gives off electromagnetic radiation based on its temperature which is roughly 6000 C plug this temperature into the StephanBolzman equation we find that the Sun is giving off about 63000000 watts per square meter Using Wein s Law we find that the peak wavelength is about 05 micrometers yellow inverse square the intensity of the radiation is inversely proportional to the distance squared lnversely proportional means that as one goes up the other goes down In the diagram a and b get the same amount of radiation but it is more intense more per unit area at a and more spread out at b I solar constant the amount of solar radiation received at the top of the atmosphere does vary some Earth Rotation axis of rotation imaginary line going through the North and South Poles that the earth rotates on o 1 rotation 1 day zenith the point directly above you solar noon the Sun is the highest it will be that day its maximum sun angle and we get the most intense sunlight at least for that day 0 the sun angle increases until solar noon and then decreases Earth39s Orbit amp Seasons perihelion when we are closest to the sun Jan 3 aphelion when we are furthest way from the sun July 4 plane of the ecliptic The path Earth takes in its elliptical orbit around the sun is on a plane an imaginary flat surface axial parallelism the axis is always pointing in the same direction toward Polaris otherwise known as the North Star Here is the pattern that Earth takes as it orbits the Sun over the course of a year Vernal March 21 Equinox Sun Summer Winter Solstice g Solstice Dec 21 June 21 Autumnal Equinox Sept 21 On June 22 give or take a day we have the Summer Solstice The North Pole is tilting toward the Sun so the Northern Hemisphere gets more intense solar radiation We also get longer days The Sun is directly at its zenith at 235 N We call this line of Latitude the Tropic of Cancer Everything north of 665 N is in sunlight all day 665 N is called the Arctic Circle Because we in the North are getting more insolation we are in summer and the southern hemisphere is in its winter On December 22 or so we have the Winter Solstice The South Pole is tilting toward the Sun so the Southern Hemisphere gets more intense solar radiation We in the North get shorter days The Sun is directly at zenith at 235 8 and we call this line of Latitude the Tropic of Capricorn Everything south of 665 8 is in sunlight all day 665 S is called the Antarctic Circle North of the Arctic Circle is complete darkness We are in winter and the south is in summer Half way between the solstices are the equinoxes September 22 is the Autumnal Equinox and March 22 is the Vernal Equinox On these days the sun is directly overthe Equator and every place on Earth gets twelve hour days In between these days the Sun is at zenith at some place in between the Tropics It is never at zenith north of 235 N or south of 235 8 This shifting north and south has an important effect on climate as we will see because the climate patterns shift with the sun Composition and Structure of the Atmosphere Thickness of the Atmosphere no definitive answer to how high the atmosphere is gases are densest near the surface and get less dense with altitude At 16 km the air is 10 as dense as at the surface and at 50 km it is 1 There is almost no gas found above 100 km but some exists Composition permanent gases 0 relatively constant proportions O evenly distributed over globe O Nitrogen 78 Oxygen 21 argon gt1 0 many of these substances are being cycled with the solid Earth 0 residence time how long gas will stay in air before going through cycle variable gases 0 a small fraction of the mass of the air but some are crucial to the operation ofthe atmosphere and to the existence of life itself 0 Water vapor averages about a quarter of one percent of the mass of the atmosphere but that varies from a small fraction of one percent in many deserts to several percent in some tropical locations 0 hydrologic cycle describes the movement of water in gas liquid and solid forms throughout the environment 0 Carbon dioxide is another variable gas It makes up only a small fraction of one percent of the air Particulates 0 Aerosols are tiny solid and liquid particles in the air excluding water droplets hese occur naturally but also are a form of pollution dust storms volcanic eruptions industry Structure of the Atmosphere 39 troposphere lowest layer where life is found 0 temperature decreases with altitude 0 where most weather is 39 environmental lapse rate rate temperature drops with altitude 65 C per 1000 m in troposphere 39 air pressure the weight of all the air above pressing down the higher you go the less air above you and therefore the lower the pressure 39 tropopause transition zone between the troposphere and the stratosphere 39 stratosphere above stratosphere 0 not much air 0 increase in temperature with height bc of absorption of UV by ozone The Ozone Layer Ozone is three 39 molecules of oxygen bound together 03 chlorofluorocarbons or CFCs are released and slowly drift up to the stratosphere where the ultraviolet radiation breaks up the molecules and these then react with ozone to break it down In high doses UV kills people fairly quickly Global Energy Balance amp Temperature Distribution solar constant at the top of the atmosphere we receive about 1367 watts per square meter per second energy balance for Earth the inputs equal the outputs of energy at least most of the time If they aren t equal then our climate warms or cools lnsolation in the Atmosphere 39 While the insolation reaching the top ofthe atmosphere is the same as when it left the Sun it does get changed as it travels through the atmosphere some wavelengths get removed Absorption done by various gases aerosols and water droplets These things gain energy and warm up and in so doing reduce the amount of energy reaching the surface Scattering Gas molecules water droplets and aerosols intercept certain wavelengths and send them out in all directions Think of one strong beam hitting the object but then many weaker beams leave it 39 direct radiation uninterrupted sunlight 39 diffused radiation scattered radiation making it to the surface shadows Rayleigh scattering 0 Some gas molecules are the right size about one tenth the wavelength to scatter certain wavelengths Mostly visible light is affected especially the shorter wavelenghts like blue At sunrise and sunset the radiation has to travel through more of the atmosphere so more of the shorter wavelengths are depleted and the longer ones like red dominate 39 nonselective scattering caused by water droplets in clouds which are larger than aerosols Clouds are white or gray because the visible light is scattered equally Reflection the wavelengths get bounced off a surface but unlike scattering where it goes in all directions the energy simply changes direction 39 Albedo is the term we use for how good a surface is at reflecting 0 Mirror 100 o o 0 Black Surface is close to 0 Transmission The energy that is not absorbed scattered or reflected is transmitted through the atmosphere relatively unchanged called direct radiation shortwave radiation insolatoin longwave radiation energy given off by Earth 39 counterradiation The longwave radiation returning to the surface Net Radiation gains minus losses of energy positive during day negative at night at the surface we have an input of shortwave radiation an output of longwave radiation and an input of counterradiation 39 Absorbed shortwave outgoing longwave counterradiation net radiation 0 Remember that absorbed shortwave is the direct and diffuse hitting the surface times the albedo Ways net radiation moves conduction heat moves through solids and the transfer of heat is from molecule to molecule sensible convection works in a similar way but with gases and liquids instead of solids sensible latent heat heat hidden in water not sensible I evaporation takes energy to lossen the molecules gt sensible to latent sweat I condensation latent heat to sensible dew surplus in Tropical areas deficit in Polar areas Greenhouse effe longwave gets trapped in Earth39s greenhouse O O
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