Geog 1000 Lecture Notes: Urban Heat Island Effect PDF

Lec 13 oct 23rd…….. Beginning of material for midterm 3 Microclimates and atmospheric circulation The urban environment Different in elements within a climate Cities are often really warm compared to surrounding environments Dusk domes exists around cities Urbanised environment...

Lec 13 oct 23rd…….. Beginning of material for midterm 3 Microclimates and atmospheric circulation The urban environment Different in elements within a climate Cities are often really warm compared to surrounding environments Dusk domes exists around cities Urbanised environment use building materials that make surrounding hotter Vegetation through the process of transpiration = photosynthesis = cooling environment (but not in cities) More sensible heat available and less latent heat transferring Urban heat island Why is UHI a problem? Strategies to reduce the UBI effect? The urban environment Urban microclimates generally differ from those of nearby nonurban areas, with urban areas regularly reaching temperatures as much as 5 °C warmer The physical characteristics of urbanised regions produce an urban heat island In the average city in North America, heating is increased by modified urban surfaces such as asphalt and glass, building geometry, pollution, & human economic activities - these all produce heat pollution Most major cities also produce a dust dome of airborne pollution trapped by certain characteristics of the Urban Heat Island City planners and architects use a number of strategies to mitigate urban heat island effects With the prediction that 60% of the global population will live in cities by 2030, and with air and water temperatures rising because of climate change, urban heat island issues are emerging as a concern Urban heat island (surface level): GTA Several degrees warmer in downtown In the air UHI is largely a nighttime phenomenon No shortwave during night time  But with urban environments those losses don't occur in the same way WHY? Summary of causes (HINT) Altered budget terms leading to +ive ΔTu-r 1.Increased Absorption Of Shortwave radiation ○ Building and cities are dark, asphalt and concrete is reradiating heat ○ Low albedo in these environment 2. Increased long-wave radiation from sky ○ Why? Air pollution (dusk dome) ○ Layer of localised GHG absorb much more escaping long wave radiation that is absorbing and sending that energy back down 3. Decreased long-wave radiation loss ○ Dusk dome again 4. Anthropogenic heat sources (urban heat island effect) Industrial kitchens, AC, etc. producing huge amounts of heat in the city 5. Decreased evapotranspiration ○ Everything abt a city does not let water accumulate ○ Water is sloped and filtered away (flooding is bad) ○ But this means no evaporation (this is why green spaces are so important today 6. increased heat storage ○ -materials that we use to build things like glass,steel ,they hold onto heat ○ Construction materials -increased permeability 7.decreased total turbulent heat transport Result of canyon geometry and limited wind speeds Construction materials -increased thermal admittance We are shielded from the wind, to dissipate heat we need wind and were not getting that in the same capacity Related features of urbanisation Canyon Geometry-increased surface area and multiple reflections ○ Decreases loss because intercepted by everything else  Air pollution - greater absorption and re-emission Canyon geometry - reductions of sky view factor Building and traffic heat loss Construction materials - increased impermeability Construction materials - increased thermal admittance Canyon geometry - reduction of wind speed Long-wave radiation balance Restricted sky view factor (the amount of sky ‘seen’ by the surface) ie. much of the L emitted is absorbed & re- emitted to the surface. ○ This is why we retain so much more heat ○ Reduces the amount of longwave loss Reduces total L[ Important factor - limiting radiative cooling at night Summary of causes 3. Decreased long-wave Canyon geometry - reductions of radiation loss sky view factor 5. Decreased evapotranspiration Construction materials - increased impermeability 6. Increased heat storage Construction materials - increased thermal admittance Geo systems Define the concepts of air pressure and wind and describe instruments used to measure each Explain the four driving forces within the atmosphere - gravity, pressure gradient force, Coriolis Effect, and the friction force Describe upper-air circulation and define the jet streams Explain several types of local and regional winds Summarise several multiyear isolations of air temperature, air pressure, and circulation associated with the Arctic, Atlantic, and Pacific Oceans Introductions The global circulation of winds & ocean currents is one of the most important outputs of the Earth-atmosphere energy system More than any other Earth system, our atmosphere is shared by all humanity ○ What happens in the atmosphere moves around Ex; As aerosols travel freely over Earth, international concerns about transboundary air pollution and nuclear weapons testing illustrate how the fluid movement of the atmosphere links humanity more than perhaps any other natural or cultural factor Atmospheric pressure and wind Air pressure - the weight of the atmosphere described as force per unit area Air pressure is key to understanding wind Both pressure and density decrease with altitude in the atmosphere Amount of water vapor in the air also affects its density Moist air is lighter because the molecular weight of water is less than that of the molecules making up dry air The end result is that warm, humid air is associated with low pressure and cold, dry air is associated with high pressure systems Weather systems take on characteristics of atmospheric source area ○ This means air mass can be warm and wet or warm and dry or cold and wet etc... Air pressure management Any Barometer Measures Atmospheric Pressure Mercury Is The Substance That reacts to changes in pressure ○ Because its a metal (extremely dense) ○ Air pressure measurement Aneroid barometer - dry (using no liquid) Today, atmospheric pressure is measured by electronic sensors that provide continuous measurement over time To compare pressure conditions from place to place, pressure measurements are adjusted to a standard of normal sea-level pressure ○ This can be difficult cause it needs to be homogenised ○ Hard to do due to elevational changes which impact pressure...this needs to be standardised Barometric pressure (at sea level): - Temperature: 15oC (59°F) - Pressure: 101.325 kPa - Density: 1.23kg/m3 Comparative Scales Millibars Inches Of Mercury For Air pressure Normal Range From 980 to 1050mb and form 29 31 inches of mercury (Hg) HurricaneGilberthad the extreme low of 888 mb and 26.23 inches of Hg Wind: descriptions and measurement Wind-the generally horizontal motion of air across Earth’s surface An Anemometer-measures wind speed A Wind Vane-determines wind direction Winds Are Named for the direction from which they originate, e.g. easterly EàW Driving forces or effects determine both the speed and the direction of winds Four forces or effects determine both the speed and the direction of winds:  Four forces or effects determine both the speed and the direction of winds: Gravitational force Pressure gradient force (PGF)- produced because of the difference in pressure between 2 points Coriolis effect- deflection of something moving Friction force- force which opposes motion Hint 1 mark easterly winds blows from east to west Pressure gradient force Pressure gradient force - drives air from areas of higher barometric pressure to areas of lower Gradient - rate of change in some property over distance Without a pressure gradient force there would be no wind, it would mean that everything has equal pressure between them Vertical air motion can create pressure gradients, too Wind This flow is wind ---> has speed and direction... a vector Thermal circulations systems occur with horizontal pressure gradients created by contrasting thermal environments In cool areas air sinks and high pressure is developed In warm areas we are warming the air which is decreasing in density and rising, this generates an airflow This is what is happening at the surface- but at the loft (atmosphere) Density changes with temp Idealised pressure (testable question)- trying to show us how wind gets started Unequal heating changes the shape and volume of air columns ★ Column A- equal amount of surface pressure and pressure 1 km aloft (in the atmosphere)  ★ Collum B- side A is being heated more aggressively than side B, this means we have greater pressure at one km, because the shape of the air column has become larger, the blue (cool) collum is more dense so you can move through it faster, but the red one is warmer so it takes up more volume ★ This generate a pressure differential aka a gradient ★ Collum c- wind is going to blow from H---L which adds mass to L but takes away mass from H ★ Pressure doesn't build up cause the atmosphere has no bounds so instead the gas is allowed to expand and grow ★ Warm air occupies larger volumes than cold air Pressure gradient PGF An isobar - an isoline plotted on a weather map connects points of equal pressure Spacing between isobars shows intensity of the pressure difference (gradient) Closer isobars denote steepness in the pressure gradient Steep gradient causes faster air movement from a high-pressure area to a low-pressure one Isobars spaced wider apart from one another mark a more gradual pressure gradient A force that has consequences Coriolis Force-makes wind travelling in a straight path appear to be deflected in relation to Earth’s rotating surface It is on Apparent Force That Affects The Direction of moving objects It apparently deflect the motion of an object This affects things that travel over long distances Artillery, air crafts, wind What does original motion mean? Northern hemisphere: curves right Southern hemisphere: moves left Equator: no coriolis effect Max coriolis?; areas or higher latitudes (north or south) Showing motion in which its deflected and which one is subject to the most intense force...which ever one is closest to the poles The coriolis force ​Apparentforce deflects moving objects to the right To The Left In The southern hemisphere Strength Is Directly proportional to wind speed The Coriolis force is dependent on latitude ​ – At the equator, the Earth’s rotation causes purely translational movement of the surface Coriolis force is zero ​ – At the poles, the rotation causes purely rotational movement of the surface Coriolis force is maximised ​ – In between, the Coriolis force is between zero and maximum Friction force High enough up there is no force of friction Friction decreases with height In the boundary layer, friction force creates drag as the wind moves across Earth’s surface But friction decreases with height Without friction, surface winds would move in paths parallel to isobars at high rates of speed Upper air winds are not affected by friction forces Rougher surfaces, on the other hand, produce more friction Forest have much greater friction that ice or snow Cities and forests have highest amount of frictions Friction force: friction between air and surface slows wind (up to 500 m above surface!) which reduces the effect of the Coriolis force Geostrophic winds Balance Between Pressure Gradient Force And Coriolis force (these compete for the direction of the wind) – Occurs where friction is negligible – Above the planetary boundary layer Surface winds Wind Speed Is Reduced By Friction Coriolis force is weaker Wind Cross Isobars At An angle Wind Spirals Into Cyclones Wind Spirals Out Of Anticyclones ○ Upper air winds travel parallel to isobars CFnm longer perpendicular to PDF Three-way balance of forces Wind crosses isobars,but still deflected from PGF Local winds  ➔ Pressure Differences because local wind sare linked To temperature differences that occur due to variations in surface properties or variations in terrain ➔ – Temperature differences resulting from variations in surface properties (HINT) ➔ Land breezes Sea breezes (hint) – Temperature differences resulting from variations in terrain During day there is warm land compared to cooler ocean This difference make high pressure over cool ocean and low pressure on hot land Aloft that effect is mirrored, this creates a circulation pattern This opposite in night Warm ocean and cool land SEA BREEZE Cause because of differences Figure 11.25a – development of a sea breeze circulation system during the day, when a thermal low-pressure system develops over the warmer land and a thermal high-pressure System develops over colder water. Figure 11.25b – the development of a land breeze circulation system at night under the opposite conditions. Mountain valley winds Mountain winds Valley winds In the day warm air rises up the slope of the mountain creating a valley wind system At night cold air flows down steep slopes creating a mountain wind Important concept in this lecture Lecure 14 Oct 25 Start of lecture packet 9 Climate through time Climate change? We are looking at anthropogenic climate change Anthropogenic climate change is outside of normal climate variability Why is climate change a major threat to humanity Humanity threatened? More than >8.2 billion! (population) Basic Human needs for survival include:  Oxygen- eco system service (for free from nature), important in nature Water- we access this from nature Food- we need large quantities of food everyday Shelter- we require shelter, we can’t sustain ourselves Clothing- we need this Sanitation- most people live in close porxiites so we need a way to keep clean ○ All of these things require energy and food Why are these not thought of in the light of climate change? Climate change Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years It may be a change in average weather conditions or the distribution of events around that average (e.g., more or fewer extreme weather events) Umbrella term Gridded climate products_ what climate looks like over the world over a specific amount of time Study of past climates uses proxies to understand what was going on in the past Weather vs. climate Weather: Observations in meteorological phenomena day to day. Climate: Observations in meteorological phenomena over a long period of time (30 years) thus a form of average. What is climatology? The scientific study of climate and climatic patterns and the consistent behaviour of weather, including its variability and extremes over time in one place or region; includes the effects of climate change on human society and culture Global climate change Climate is not static: - varies from one place to another (spatial) - varies over time (temporal) Variation over time can be due to: - natural phenomena (dominant on long-term) - anthropogenic forcings (dominant on short-term)  We want to understand how changes in the system comes through How humans change climate and how climate varies on different cycles How do we know climate has changed in the past? Range of evidence exists to allow us to reconstruct the Earth's past climate Grouped into three general categories: Meteorological/instrumental records What we have rn, seeing how things have changed in various places, its a very defined record that update hourly or sub hourly Historical records The study of past societies and culture gives us a good idea of what climate was like We can see this change by the success (progression) of agriculture Ex; extensive wine consumption in england cause of the type of agriculture thats there Not super specific but gives us an analog into to this Physical and biological recordsà paleoclimatology This include the scientific analysis of things like past creatures by looking at things like oxygen and isotopes in water Time The indefinite continuous progress of existence and events in the past present and future regarded as a whole. Difficult concept to understand without a reference point. Time is not constant #complicated Influenced by the mass of an object or velocity (Time Dilation) Time is important Reference is important (this is why time is important) Time scales are meaningful because of reference points Examples include A.D., B.C. and B.P. (referenced to 1950) These time stamps are not meaningful to this context Not overly meaningful to science The big bank theory slide Geological time scale slide This is an organisation, there are not standard intervals between them  This is not constant, its broken down according to significant events that have been recorded in earth's history Sources: rocks and fossils Watch life or something by morgan freeman We are at the end of the holocene and we have entered the anthropocene In the anthropocene the biggest influence done to earth today is because of human bi products Tools in paleoclimatology Shows us date range we have to use tools to examine climatology of the past Satellite record- great but this era only goes back to late 1950’s Instrument records- great cause they give us high res data Doc evidence- goes back a few thousand year, human culture is needed for this to exist (art, language etc..) Tree rings- growth rings are influenced by the environmental conditions, and can be used as a proxy to understand how things were different in the past Polar ice cores- drilling into to old glaciers (greenland/antarctica) Lake sediments- the rates in which sediments are held down in lakes, some as polar ice cores Pollen- same tells us abt conditions of past Ocean cores- tells us abt conditions of past Sedimentary rocks - tells us abt conditions of past Lake sediments slide Lake fills up with everything that goes into the lakes (pollen, sediment, grain crops) We can core the lake and take a cross section of what it looks like and analyze how its linked to climate Life jacket boat slide They used a piston corer to get a cross section of the lake sediments Glaciers and isotope dating Good example of how we can identify climate changes Heavy water: used to cool nuclear reactions and exists in weather systems isotopes - chemical that contain more neutrons than what the normal would typically be They evaporate less and are ionically heavier Have to know- bubbles of atmosphere to understand onc of gasses in the past Pictures of isotope They were taking a glacier core so that it could be analysed Glacial and interglacial periods We want to understand the seasonal variability that existed in the past compared to now Glacial Periods (ice aged) Periods of time where continental ice sheets dominate polar areas (100 ka) Interglacial Periods Periods of time when continental ice sheets retreat are relatively warm between glacial periods (20 ka – 40 ka). Interglacial period happen BETWEEN glacial periods What is the big deal about climate change Last Glacial Period (maximum)–temps only cooled~ 5°C in some places! RESULT: ice covered 1/3 of the earth’s landmass during the maximum extent of the last glacial (Pleistocene ~18ka) Including all of canada completely covered in ice Lots of moisture deficits in areas that were not covered in ice (yukon/siberia) There was a land bridge from siberia into the americas (north america) so nomadic tribes came in and populated Sea level is lower today: cause glacial ice is running off in the ocean Degree of change At least four major glaciers in North America (latest to oldest): Wisconsinan Glacial- most recent 18,000 years ago Sangamonian Interglacial Illinoian Glacial Yarmouthian Interglacial Kansan Glacial Aftonian Interglacial Nebraskan Glacial Presence of these glaciers shaped a lot of how the world is shaped today Permafrost is thicker in siberia A lot of our fertile farmland we also owe to glaciers cause they break up rocks and release nutrients Petrified wood Fossilised tree Degree of change Last major warm interval was the Pliocene 3-4 million yrs ago (Pliocene age tree-line deposits on Meighen Island in the Canadian Arctic) Lecture 15 oct 28…. Degree of change Should be able to adequately explain what is happening and know why the climate change today is different from the climate change in the anthropocene First major northern hemisphere glaciation began during the Pleistocene ○ Humans have only been alive for the last 200,000 years ○ Alternation of glacial & interglacial periods began about 2.4 MY ago ○ Global temperature difference between glacials (colder) & interglacials (warmer) is about 5°C- this is a global average that we see in temp During glacial periods, ice covered up to 34% of the globe This takes water out of the ocean resulting in lower saltier water Changes the planet's reflectivity, so it becomes much colder Presses the weight of the continents down Ex; the canada that we see today is “rebounding” like the hudson bay being very shallow (it used to be a glacier) In another 10,000 years the hudsons bay may not exist or there may be little islands there aka. Rebounding Pictures what canada wouldve looked like The current interglacial, which began about 10-12000 years ago, is called the Holocene Within the Holocene, temperatures were about 2°C warmer than at present about 6500 years B.P. during the “Climatic Optimum” ○ Continent shapes ice sheet that broke up and formed many freshwater lakes throughout Temperatures were up to 1°C cooler than today from 2500- 1200 B.P. (before present) Temperatures were about 0.5°C warmer from 800 - 1200 A.D. (Medieval Warm Period - Vikings in North America and Greenland) Little Ice Age occurred from 1400-1850 A.D. with temperatures up to 1°C colder than at present and advances of glacier fronts all over the world Warming began in the late 19th Century and peak temperatures reached in the 1940s followed by a decline to the early 1970s and an alarming increase since then Change mechanisms Variations in sun’s energy output Sun is the primary driver of climate Sunspots vary in an 11-year cycle They are magnetic disturbances that occur on the surface of the sun There have been periods, such as the (HINT) Maunder Minimum (1645- 1715) when sunspot activity was very low and global temperatures were cooler Picture of sunspots Variations in earth-sun geometry (very important) Milankovitch- important to understand the geometry behind solar physics The energy received at the top of the atmosphere will vary if the motion of the Earth relative to the Sun is not constant Milankovitch (1930) showed that three variations in the Earth’s orbit, operating over different cycles result in about a 5% variation in the energy received, especially at high latitudes Be able to talk about each cycles and how they work Variation 1: Eccentricity of the orbit (stretch) Orbital eccentricity 90,000 year cycle; orbit changes from nearly circular to more elliptical. (circular orbit = constant amount of radiation received through the year) Our orbit goes a little further away and become more elliptical (oval) This change causes greater eccentricity and greater seasonality in one hemisphere and reduces it in the other Greater seasonality: more intense summer and more intense winter Change in tilt of axis of rotation (roll) 41,000 year cycle; varies from 22° to 24.4°(currently decreasing from 23.5°) Greater tilt causes greater seasonality in both hemispheres (zero tilt would mean no seasons), less snow & glaciers recede Axial tilt picture Precession of the equinoxes (wobble)  22,000 year cycle; affects the timing of aphelion and perihelion relative to the seasons Important: Earth is closest (14.7 x 107 km) to the Sun on Jan. 3, furthest (15.2 x 107 km) on July 4. Helps un understand why antarctica is colder than the north pole The southern hemisphere is predisposed to being colder Winters are milder & summers cooler in the Northern hemisphere (seasonality decreased) Winters are colder & summers warmer in the Southern hemisphere (seasonality increased). Precession of the equinoxes affects the two hemispheres differently ~10,000 yrs ago the reverse was true and the Earth was closer to the sun in July Combined effects of 3 orbital cycles (identified by Milankovitch) can explain the overall pattern of warming & cooling, but not the speed of onset & end of glacial periods. Land and polar position make a big difference (land close to the poles so you can accumulate snow and have seasons in these areas) There must be internal feedback mechanisms to amplify the external orbital changes Milankovitch Summary - It’s all about the amount and spatial variability of incoming radiation and climate change Very super very important Milankovitch theory: interaction results in a 96000 year climatic cycle simply through changes in the insolation Internal changes within the earth’s systems Possibilities include Formation of mountain barriers (e.g. Himalayas and the Tibetan Plateau over the long term, this area is seemingly close to the equator but is really cold due to high elevation) Volcanic eruptions injecting dust into the stratosphere Changes in ocean currents and salinities ○ Changes in the labrador stream (cold water stream), leaving people freshly farmed land fully submerged Massive calving of ice into the North Atlantic (towards the end of the last glaciation) Positive feedback End of lecture packet 9 Lecture 16 Clean room notes Pat (clair) paterson? World began oct 22nd at 6pm on a saturday Deepest layers of rock are not the oldest things on earth Between the orbits of jupiter and mars there is evidence of the formation of earth Calculating the amount of uranium turned to lead should tell us the age of the earth Pat kept getting inconsistent measurements compared to the guy measuring the uranium He built the worlds first ultra clean room He used a spectrometer Lead mimics other metals in our bodies like zinc and iron Clean Room Video Highlights & Questions How was the “original” age of the earth established? James Usher added up years in the bible based on an event that occurred on a known date, the death of Nebuchadnezzar in 562 BC Then used knowledge of generations to establish the Earth was created on Oct 22nd in 4004 B.C. (a Saturday, at 6 pm) Why could we not simply just add up all the rock layers? Sedimentation rates varied substantially Where was the “stuff” left over from the creation of the solar system? Asteroid belt Explain how we can use uranium (U) to lead (Pb) to calculate the age of the Earth Atomic decay Why can’t we use rocks on Earth to date the age? None survived Why was the concentration of Pb always off in all of Pat’s tests Too much background Pb present What instrument does Pat use to measure the amount of elements in a sample? Mass spectrometer Roman plumbing, why Pb? Cheap, slaves, easy to work with Why is Pb toxic to humans? Gets into cells and does not allow enzymes to do their job What was the additive used in leaded gasoline? ○ Tetraethyl lead ○ Fat soluble Who was Robert Keyhoe? Scientific expert for the Pb industry How did Pat know that Pb levels in nature were typical but not natural? Deep v. shallow ocean and glacier ice Physical geography Consists of three divisions: biogeography, climatology, and geomorphology The earth atmosphere system Planets A planet is a celestial body that: Is in orbit around the Sun Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape) Has "cleared the neighbourhood" around its orbit Solar system Made up of eight planets There are four terrestrial planets (Mercury, Venus, Earth and Mars) There are four jovian (gaseous) planets (Jupiter, Saturn, Uranus and Neptune) Three dwarf planets Ceres, Pluto and 2003 UB313 Separating the terrestrial and jovian planets is an asteroid belt The solar system Earth interior Pre 2006: Oldest dated rock on earth Acasta gneiss found in Northwest Territories, Canada Dating methods: radioactive decay of Uranium and Thorium to Lead 3.96 billion years This vast time span encompasses: Ø our planet’s formation (its oceans, continents and atmosphere) Ø the origin of life and the evolution of the biosphere to its present complexity. To cope with such long geological time, we divide it into manageable time intervals based on natural transitions Eons hundreds of millions to billions of years Eras many millions of years: distinctive fossil records Periods millions of years: distinctive rock units Epochs few million years Ages thousands of years The fossil record in rocks deposited in the shorter time intervals is well-constrained:  we can correlate these units globally we can reconstruct the appearance & conditions of our planet for many hundreds of different time slices Earth is a dynamic planet Earth’s surface (crust) is in an ongoing state of change formed, deformed, moved, and broken down over short to long time periods (millions of years) Lecture 17 Two types of processes/systems: 1) endogenic: internal system flows of heat and material from below Earth’s crust powered by RadioactiveDecay Mostly molten iron here Deepest hole we've ever drilled is only 12 km below the earths surface eg. mountain building, earthquakes, volcanoes 2) exogenic: external system the motion of air, water, and ice powered by Solar Energy eg. all processes of landmass denudation such as physical and chemical weathering, landslides Endogenic system Heat energy migrates outward from the centre by Conduction and by Convection in the more fluid or plastic layers in the mantle and nearer the surface Study of the Earth’s structure: via seismic tomography Deepest mine ~4km Deepest drill holes ~12km Earths crust Crust – outermost, rigid (because it's solidified) layer relatively thin – thickness varies Oceans ~8-10km, Continents ~40km Continental crust - generally of lower density; 2.7 g cm- 3  - Granite Oceanic crust – higher density; 3.0 g cm-3 - Basalt Earths interior Mantle: Mostly solid ~2900 km thick very thick T & P ­towards centre E transfer towards surface Asthenosphere: partial melting zone Lithosphere: rigid layer Core: Interior is layered Inner core: solid iron, high pressure won’t let rocks melt T ~2500°C Outer core: molten iron, lighter density, high T’s cause rocks to melt This allows movement of convection currents which power the magnetic field which allows us to block harmful radiation and navigation Earth's magnetism Magnetic field & magnetosphere generated by fluid outer core Thermal & gravitational energy Þ magnetic energy North magnetic pole: moves Geomagnetic reversals Average period of reversal: 500,000 yrs Varies Tool for dating rock units, understanding plate tectonics & movement Shows su the dynamic for earth Geological cycle Endogenic system: building landforms (things that happen deep in the earth) Exogenic system: eroding landforms (becomes subject to external processes that are mostly weather based) Heat from solar energy & internal heat Tied to hydrological cycle (water processes), rock cycle (rock types & transformations) & tectonic cycle (heat, energy & material recycling) Endogenic builds up landforms Rock formation Plate tectonics Isostatic adjustments Exogenic processes Weathering Mass wasting Erosion New places Hawaii Himalayas West coast of south america: deepest parts of the ocean The rock cycle (understanding major elements HINT) 8 major elements: O, Si, Al, Fe, Ca, Na, K, Mg, others (minor) Minerals: pure, natural compounds with specific chemical formula, crystal structure with defined symmetry Rocks: group of minerals or solid organic matter Rock cyle diagram good testable question HINT Igneous rocks are volcanic origin = liquid and then solidified on the surface Most of our rocks are igneous young rocks Metamorphic rock- subject to tremendous heat and pressure ○ The chemical nature of the rock is changed BUT the rock does NOT melt ○ Rocks and minerals Rocks vs. Minerals? All ultimately derived from magma Main elements in crust, same as those in magmas Rocks vs. minerals (all arrive from magma) Most of all rocks will be igneous in nature Rock types Sedimentary rocks- a rock that has layers and settles out Sedimentation (bonding of the small rocks) & lithification Stratigraphy: age relationships Clastic (bits of solid rock) vs. chemical sedimentary rocks (evaporsomething- Igneous rocks (90%)- any other kind of rock that has melted and solidified Small & large grained rocks: cooling rate Intrusive (HINT; those that form under the surface of the earth & extrusive rocks (from on the surface of the earth): batholiths, dykes vs. volcanoes Felsic or mafic: elemental contents The majority of the earth, including all of the mantle and oceanic crust, and most of the continental crust consist of igneous rock Igneous rocks Metamorphic rocks Changes by temperature & pressure Regional vs. contact metamorphism Foliated or not: mineral alignment foliation (squiggles in rocks, go through intense heat and pressure but they don't completely melt) They come from parent material rock- #parentrock HINT- knowing the parent rock and what in can turn into Metamorphic rocks gneiss , marble, slate...(HINT) The rock cycle Sedimentary rocks are young If metamorphosis rocks melt they become igneous Lecture 18 nov 6 Techtronic movement Continental drift (1912) proposed by Alfred Wegener (1880-1930) Continents slowly drift apart Theory not widely accepted until 1950 Continental Drift: The Theory of Plate Tectonics Theory first developed in the early 1900’s by Alfred Wegener (1880 – 1930) Argued that the Earth’s continents were once joined together as one (Pangea) Over millions of years the continents have moved apart Wegener could not explain the mechanism of his theory Polar position: can be very important to influence earth's climate Big impact on physical features (tells us info about when were gonna have glacial periods) Polar position give glacier’s a rooting zone Malankovich Plates and plate boundary Surface expression Oceanic crust (more dense) ends up under continental crust (less dense) and continues to submerge deeper into the crust As they go down they are subjected to a bunch of heat which creates magma This process is shown on the surface (surface expression) though volcanoes mountains etc Speeds vary from 1 to 12 cm a year Different locations have different speeds Changing orietnation Plate Tectonics Mechanism Upper mantle – slow flow Convection cells:  Heating of mantle material, Hot material rises Movement outwards, Cooling Eventual collision & subduction Gravity push/pull: lava up, weight of thickening plate down Plates and plate boundaries Speeds: from 1 to 12 cm/yr Different directions, different speeds Changing orientations, locations over geological time: evidence Wilson cycle Wilson cycle: supercontinents (1966) 5 previous in 3 billion years (Pangaea) Act as insulator: mass traps geothermal heat in Earth Steps in cycle: assembly, stability, splitting, to reassembly: 500 MY cycle Can be incomplete assembly Evidence: 6 orogenic episodes Terranes, exotic terranes Plate boundaries 3 main types: convergent, divergent & transform  Understanding the interaction between plate boundaries 3 main types: convergent- things coming together (indian plate to eurasia) Divergent- away from another (east africa) Transform- moving together Arc islands Ex; illusion islands in alaska When two continents run into each other: mountain (himalayas) When oceanic plate run into each other: volcanoes What about oceanic plates and continental? (west coast of america, deep trenching) Transform faults: faults that move relative to each other Crust deformation (HINT), difference between and understanding the surface expression 3 main stress types: Tension: stretching- crustal thinning Compression: shortening- folding (a measure of the material properties) ○ Faulting- normal fault (position of head wall changes...projected in which something falls down ○ Reverse fault- something going upward Shear: twisting- pushing but not uniformly pushing Strain: response to stress Folding: bending Faulting: breaking Folding Compression at convergent plates: folding Anticlines & synclines (HINT) Broad scale warping: basins & domes Plastic ruler Faulting Fracture of material + displacement relative to the fracture in the land Normal fault: tension Thrust fault: compression Strike-slip fault: shearing Glass ruler Lecture 19 nov 8 Orogenesis endogenic processes- processes in which we build up the landscape Mountain building: folding & faulting, plate collision, addition of terranes, volcanic addition, uplift ○ Examples of orogenesis (endogenic processes) Continent to continent, ocean to continent, ocean to ocean, Rocky Mountains Appalachians Himalayas- young, haven't gone through orogenesis Earthquakes Series of shocks caused by movement in crust or upper mantle Often along fault lines Stresses pass threshold point: sudden failure Focus: point of failure Epicentre: point on surface above focus (where the earthquake is most intense) ○ HINT Surface expression of gradual internal processes Scale (magnitude) varies: damage caused, 10x increase each level Worst: deepest foci, greatest stresses (the energy you put on something), produce greatest strains (the stability) (displacements, deformation) Seattle will be annihilated at some point in the next hundred years Tokyo is the most prepped place for an earthquake on earth  Aftershocks: further slippage along fault line Seismographs: recorders Volcanism Magma (molten rock) rises to the surface from the asthenosphere eruption – When lava (magma) is expelled onto the Earth’s surface while still molten -Gases, pyroclastics also ejected -May build up and break down volcanoes Throughout the world there are more than 550 active volcanoes and 10s of thousands of extinct ones Where? 1) Subduction boundaries 2) Sea-floor spreading centres 3) Hot spots Mid ocean ridge system surfaces in iceland Iceland also called a hot spot Types of volcanic activity Depends on magma’s 1) chemistry 2) viscosity- how thick the liquid is Low viscosity magma- gentle lava features, less explosive potentials Effusive: low-viscosity magma, < 50% Si, rich in Fe and Mg Gentle (generally), lava pours out on surface with rel. small explosions (less gas) Sea-floor spreading centres, Hot spots Explosive: high-viscosity magma, 50-75% Si, high in Al found in subdection zones HINT Dramatic, explosions of built-up gases, lava, & pyroclastics Subduction zones Shield volcanoes Basaltic lava hot, fluid Large, expansive flows Less violent Associated with hot spots and spreading zones (oceanic crust) (HINT characteristics of diff volcanes and lavas) Large  horizontal dimension (10’s km) successive eruptions of lava Gentle slopes (2-10°) Iceland is a hot spot example Hawaii is a hotspot example (HINT) Volcano Composite Volcano example: mt fuji subduction zones lava andesitic, to ryholithic viscous, or explosive Steep (10-35°) and high elevations (a few km’s) layers of lava, tephra Sills and dykes in subsurface Very symmetrical Mt. St. Helens, Washington: 1400 m Large eruption in 1980 57 people killed Recent volcanic activity: 2006, 2008 Cinder cones Small features Purely loose tephra Built around single vent Lava flows rare Usually, a cone crater Steep sided 25-30° Caldera Steep sided, circular depression Collapsed volcanic cone Subsidence: lava drained from magma chambers, or large volumes of tephra ejected Destruction: by violent eruption- St Helens Lecture 19 November 18th 1. Essay style- 5 marks (element from the clean vid,can find through lib) 2. Essay style -3 marks (content of the clean room video) 3. Essay style -12 marks (idea of natural climate variability) 4. 5 marks- matching elements(geologic time) 5. Matching elements-3 marks (natural climate variability) 6. Matching elements-8 marks (solar system) 7. Matching elements-6 marks -rocks 8. Matching elements-9 marks -rocks 9. Matching -3 marks rocks  10. Matching -7 marks -rocks 11. Matching- paleoclimatology-9 marks 12. Multiple choice -general 13. Dating 14. Mc climatology 15. 15. Multiple choice - climatology 16. Natural climate variability 17. Matching elements - surface expression of natural variability 4 marks 18. And 19. -urban heat island effect -multiple choice 19. Urban heat island effect -mc 1 20. Matching elements - volcanoes 21. Drag and drop element questions -coriolis effect 22. Drag and drop element-circulation pattern-4 marks 23. 24. Drop down arrow matching- 25. mc - Natural climate variability 26. Mc- 1 mark-volcanic morphology 27. Mc- 1 mark-volcanic morphology Tutorial exam 3 Land sea breeze Day;cool breeze from over ocean blows island Night: cool breeze over land blows over ocean Understanding when is it high pressure and low pressure...the difference between the pressures between day and night Relative humidity Ratio of water vapour currently in the air compared to the amount at saturation ○ -warm air can pull more water(high saturation vapour pressure) relative humidity is highest during the day or at night Humidex- relates heat sensed to temp. And relative humidity Past climate Which is the most recent? Oldest? Know which ones show us the most recent vs. the oldest tools in paleoclimatology Glaciers and interglacials Tmep difference between glacials and inner glacias is 5 degrees BP = before present = 1950 (how many years in past relative to 1950) Wisconsinan glacial Sanagmonian interglacial Illianion glicial Yarmouthian glacial Kansan glacial Aftonian interglacial Nebraskan glacial Climate change mechanisms Changes in solar output -Solar minimums and maximums During maximums there is more sunspot activity and the opposite during minimums Milankovitch cycles (VERY IMPORTANT) Eccentricity Tilit Presession Volcanoes Mountain building Changes in ocean currents Eccentricity Factor- changes in the shape of earth's orbit Range- (oo.00-0.06) 20%- There are times of the year where the orbit is further or closer to the sun Cycle length; 90,000 years (know this) Effect: when eccentricity is high there is more seasonality in one hemisphere than the other (know why) Tilit Factor change in degree of the earth's tilt Range: 22-24.4 degree (currently 23.5) Cycle length: 41,000 year cycle Effects: great tilt causes more seasonality in both hemispheres (longer days in summer, and shorter days in winter) Precession (wobble) -factors; movement of the dates of perihelion and aphelion and wobble of the tilt Cycle length 22,000 yeaRS Effects: works with eccentricity to determine which hemisphere will have greater seasonality In northern hemisphere right now we have less seasonality Clean room video Uranium and lead dating to calculate the age of the earth (4.6 billion years old) They look, how how much uranium and lead atoms are in rock, to tell the age because overtime uranium decays into lead Lead levels are typical but not natural ex; leaded gasoline Planets Terrestrial (rocky) Mercury Venus Mars earth Jovian (gaseous) Jupiter Saturn Uranus Neptune Geological time Eons- hundreds of millions to billions of years Eras- many millions of years Periods-millions of years Epoch-fe million years Ages- thousands of years Rocks and minerals Study of rocks- petrology Study of minerals- mineralogy Chemical composition Rocks: don't have definite chemical composition minerals : do have definite chemical composition Colour  rocks : not always the same Minerals: colour is the same Shape Rocks: no definite shape Minerals: definite shape Fossil Rocks: has Minerals: none Examples Rocks: limestone, basalt, claystone, coal Minerals: gold, silver, fluoride Igneous solidification and crystallisation from molten magma Intrusive -cooled inside earth ,large crystals(granite,gabbro Extrusive-cooled outside earth-small crystals Rhyolite ,basalt,obsidian Sedimentary Parts of other weathered rocks sealed together Forms of strata- different layers of rock (sandstone, shale, conglomerate...all examples of clastic rock) Clastic -made from pieces of older weather rocks ○ -sandstone,shale,conglomerate Chemical- precipitate from solution -limestone Biogenic -dead things cemented under pressure -coal Metamorphic Physical and or chemical composition altered through intense or pressure Foliated-uneven pressure,banding ○ -gneiss,schist,slate Non-foliated-equal pressure,nobanding ○ -quartzite ,marble Stress and strain Stress: the force that affects an object  Applies pressure on rocks 3 types: tensions (stretching) compression (shortening) and shear (twisting) Strain- landforms that occur from stress ○ A measure of shortening, stretching, and or twisting of rock ○ 2 types ○ folding (ductile= can bend without breaking) and faulting (brittle) Volcanoes Shield: basaltic lava (which is hot and more fluid) Less violent eruption, mainly lava flows Associated with hotspots and ocean spreading zones (ex; hawaii) They're very large 10 km horizontal with gentle slopes Composite Located near subduction zones Ex; mt saint helen, washington Viscous laval (more thick) Eruption is explosive (lots of ash in atmosphere) Very steep, low horizontal area Very symmetrical Cinder Cone Smallest Built around single vent with steep sides Lava flows are rare Usually have a cone crater Purely loose tephra(fragments of rock ejected by volcano) Ex; wizard island in crater lake national park 2