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LECTURE NOTES February 8, 2009
HYDROSPHERE – Wondrous water. Earth’s Hydrosphere and urban settings
Announcements… Labs and homework – look good to me
REMINDER: Goals of the course… two years from now when you’re asked why some city is experiencing some crisis or why some city has coped with an environmental challenge… IF you automatically think Earth systems thoughts… and run through a checklist of geosphere, hydrosphere, atmosphere, biosphere, and anthrosphere… you’ve successfully completed the course, and congratulations.
Announcement… a problem … Presentation dates… Can all the March 3 folks switch with the March 8 folks?
Announcement… FIELD TRIP DATES: SCHEDULE – April 10 and 11. A 4-hr field trip. Morning or afternoon Saturday; Morning or Afternoon Sunday.
Last time's GREEN SHEET requested more information on three topics: (a) Coriolis; (b) latent heat; and (c) gradients. REMINDER… what is the course called… why are we learning this… so all of these requests for information are right on target.
(a) More on Coriolis…. Christopherson figure 4.9.. MandM Planetary Circ You understand Coriolis when you can explain why low pressure systems of Northern Hemisphere “turn counterclockwise” and high pressure systems “turn clockwise.” Weather in the news… breakouts of Arctic weather related to “negative” meaning weak Arctic…
(b) More on latent heat… Christoperson figure 5.4 To understand LATENT HEAT it’s wise to remember GEOG3330 science concept #1 Consider different energy forms… Two concepts to consider at the same time… (a) temperature of a mass measures faster movement of molecules (thermal energy); (b) the physical “state” of a mass (solid, liquid or gas) also involves energy… latent energy.
(And… don’t let thoughts of the (c) dew point / humidity / condensation get in your way.)
LATENT HEAT – “hidden heat”… ever heard of “latent anger” … hidden anger or … latent potential = hidden potential. Changing phase … of ice to water to water vapor takes energy. That energy is “hidden” energy and called latent heat. Ask yourself… how does sweating make you cooler? Evaporation is a ‘cooling’ process. Energy leaves your skin cooler. Energy has transferred from the water at your skin into water vapor in the air. Your skin feels colder. That energy now is latent heat in the water vapor of the air. Evaporation is a cooling process.
Same concept with a glass with water and ice. Two concepts to think of at the same time. THERMAL energy transfers via conduction and convection… the water gets colder. However there’s also a transfer of LATENT heat as the ice melts. As ice melts from 32 degrees to 32 degrees, the temperature is not changing but energy is exchanged to change the phase of the ice. It takes energy to break the bonds of the ice molecules and energy is absorbed in the process. So, like evaporation, melting is a cooling process. Your drink gets colder. The water has the latent heat.
Cities generate THERMAL heat by their activities. THERMAL energy transfers by convection / advection into the atmosphere by convection. Cities also affect the LATENT heat in the atmosphere. As water in cities is transformed from liquid water into water vapor, LATENT heat is absorbed and the atmosphere has more LATENT heat. REMINDER: It’s a system.
Cities and latent heat make a good example of a feedback loop. Cities metabolize energy. Energy comes into a city in several forms (chemical, thermal, electrical… ). Cities use energy (transform it) and this affects the atmosphere; and cities waste energy into the atmosphere (hot gasses, hot particles, …). The THERMAL energy of the atmosphere is raised by convection and conduction and advection. AND the heat capacity of the atmosphere is increased by transfer of LATENT heat into water vapor. More energy in the atmosphere, more movement of molecules of the atmosphere, more capacity for holding moisture… positive feedback loop. During thunderstorms, water vapor condenses releasing (lots of) LATENT energy. Urban heat islands Urban rain NASA-UrbanRain-EarthObservatory.mht LINK
(c) More on gradients… great word… Grade of a hill. Grade as a scale. Grade as next level. Gradient. Steep gradient of Interstate 80 to Park City. Think contours.
FROM MERRIAM-WEBSTER... GRADIENT - Function: noun Etymology: Latin gradient-, gradiens, present participle of gradi Date:1835
Final set of announcements… URBAN ENVIRONMENTAL GEOGRAPHY – SCIENCE CONCEPT in the news. EXPLAIN science behind... .
TODAY’S.. BIG SCIENCE CONCEPT(S) … today is Monday, lecture day, concept day
But first… what are the two BIG SCIENCE CONCEPTS we’ve already covered. (1) ----- hint… it’s about energy. (2) ----- hink it explains why hot air balloons rise
They are HUGE concepts and explain so much. GREEN SHEET - 2 minutest to think of an example that affects “your urban setting” BIG SCIENCE CONCEPT #! - ENERGY transformations… energy “into” and “out from” your city. Please state the concept… Energy is neither created nor destroyed in a closed system. Give an example for your city.
BIG SCIENCE CONCEPT #2 GAS LAW: DENSITY, MASS, VOLUME, PRESSURE, and TEMPERATURE are related. Change one, change at least one other. Please write the equation. Give an example for your urban setting. LINK GA
Said differently: BIG CONCEPT #1 – Energy is neither created nor destroyed in cities, but its form has several expressions. BIG CONCEPT #2 – Physical characteristics of bodies (air for sure, and to a lesser extend fluids and solids) include density, temperature, mass, volume and pressure and these characteristics are related. When one factor is changed, it affects others. What should you know? Mass / Volume = Density Change pressure or temperature of something and its density will change Effects of pressure and temperatures on gasses are large (Gas Law) and less for liquids and even less for solids. Greater pressure, higher temperature Less volume, higher temperature Why? Higher temperature means faster motion of molecules… Increase temperature and… increase volume… if other factors stay constant Increase temperature and decrease mass/volume Meaning, increase temperature and decrease density Colder bodies … more dense (However… water and ice have some exceptional characteristics… ice… expands as cools… at least for some of the range of temperatures)
FOR TODAY… and from Christopherson Ch 6 and 7. GEOG3330-BIG CONCEPT #3 – Water Cycle. GEOG3330-BIG CONCEPT #4 – Budgets… water budgets = The Water Equation… and other budgets
Chapter Six of workbook – Encounter Geosystems Water cycle… precipitation, evapotranspiration, water balance, Chapter Seven of workbook – Encounter Geosystems Climate systems and climate change Climate classifications – WebCT power points… accessible? Climate change – power points on WebCT
Ten concepts: Hydrosphere and urban environmental geography
CHRISTOPERSON - Overview slide… BIG CONCEPT #4 – Budgets, specifically, water budgets… more later but as example… Water Storage = the difference of what comes in and what goes out. Less water in. Less water stored. Less water in the reservoir. Does this matter to cities? Yes, some more some less. Las Vegas? SLCity? Chicago? Tampa? NYC?
WATER CYCLE SURFACE WATER … numbers on Christopherson show percentages. Add evaporation sources and get 100%. Same for precipitation. LINK to USGS version of the water cycle. Schematic. Complex
EXAMINE budget for surface water… LINK to ESE version for SLCounty
Water is called surface water if it’s on Earth’s surface (but not an ocean); if it’s liquid … (discuss frozen lakes in winter)… and, expecially if it is moving. PRECIPITATION… then Surface runoff – Overland flow Channelized flow – into channels, streams Lakes (open versus closed basin lakes) Oceans (can be considered “sinks”. Does this matter to cities? Yes, and to some cities more than others.
SOIL WATER BUDGET CONCEPT – Christopherson complex slide. It shows: TWO CONCEPTS… (a) some surface water moves into land surface… percolation… to becomes ground water. (b) concept of a “budget” –
First of slides … surface water into ground. Earth materials… bedrock versus sediment. If it’s loose, its sediment. All sediment comes from bedrock. Slide shows surface water into soil / sediments / dirt … unconsolidated matererial of Earth’s crust (versus bedrock… the firm continuous coherent part of Earth’s crust)
Next Christopherson slide… busy and about soils… so… first discuss budgets in general. The Water Equation. LINK to GA summary of water equation Does this matter to cities? YES… flooding… Example, Great Salt Lake, Salt Lake City in the 1980s and now. Great Salt Lake. Change of storage, meaning volume of water in Great Salt Lake, results from an increase in inflow, or a decrease in outgo, or both. Year by year, Great Salt Lake fluctuates about 2 ft, up and down, seasonally. Over the past century and a half, the lake has fluctuated about 20 ft. Over the past 3000 years the lake may have fluctuated about a hundred feet, but that is still not well-defined. Over the past 15,000 years, the lake has changed 1000 ft. And that brings us to climate change, the Ice Ages, and Lake Bonneville. 1980s WET CYCLE and into the present CourseLINK to GSL Hydrograph Water Balance during 1980s wet cycle Alternatives considered to control the flooding of Great Salt Lake during the 1980s CourseLINK again Water Balance during 2000s drought cycle USDA stream forecasts WebLINK for
BACK TO CHRISTOPHERSON… BUDGET of SOIL WATER Next slide… precipitation; then evapotranspiration; then measuring device for water loss in soils; then types of soil moisture; then soil-moisture availability (geosphere – hydrosphere) relationships; Does this matter to cities. Yes, and to some cities more that others. Series of graphs.
FROM SOIL MOISTURE TO GROUNDWATER RESOURCES. Does this matter to cities, and do cities change relationships… yes.
CITIES AND GROUND WATER we'll get into this over the next weeks. Here are some examples of how cities change components of their region's water balance. (Slides for later). OFF-LINE LINK to Goudie's Ontario... effects on recharge. OFF-LINE LINK to Goudie analysis of Ontario... city and water cycle. Water balance. OFF-LINE LINK to openings... saturated versus not adapted from AGI OFF-LINE LINK to cross section saturated versus not adapted from AGI GROUND WATER, Salt Lake County as a (difficult, complex) example.. LINK to overview of SL County surface water in Utah adapted from DNR Tech Pub 31 LINK to detail of SL County surface water adapted from USGS Water Supply Paper 2232 and DNR Tech Pub 31 LINK to Precip of SL COUNTY adapted from DNR Tech Pub 31 LINK to Bedrock vs Sediments SL County LINK to Map of SL County adapted from USGS Water Supply Paper 2232
SURFACE WATER – GROUND WATER COUPLING What is meant by "gaining" and "losing" streams, adapted from USGS Water Supply Paper 2232 Different reaches of one stream may gain or lose from ground water adapted from USGS Water Supply Paper 2232
GROUND WATER AND SURFACE WATER ARE A COUPLED SYSTEM - SUMMARY Salt Lake County: Surface and Ground water coupled system
CHAPTER 7 – CHRISTOPHERSON. TWO THEMES of the book and workbook: (a) climate systems and (b) climate change. Powerpoints of climate systems say it well and sufficiently. Minimal GA additional notes…
Earth’s Climate System – powerpoint – BUDGET; ENERGY transformations; DENSITY mass volume temperature relationships; WATER cycle.
HOW affect cities…so many ways.
MICROTHERMAL climates … most cities Humid continental … hot – summer … SLCity Humid continental … mild summer climates Subarctic climates… cool summer climates Extreme subarctic … cold winter POLAR ARID and SEMI ARID
NEXT TIME: GLOBAL CLIMATE CHANGE. ... Cohen powerpoint. … |
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