Final Test Flashcards
Water in the Atmosphere, at Earth’s Surface, and Subsurface (notes)
Chapter 7 - Atmospheric Moisture and Precipitation (textbook)
Chapter 15 - Groundwater and Karst Landscapes (textbook)
Basic Physical Properties of Water
Hydrogen Bonding
High Surface Tension
Capillary Action
High Heat Capacity
H2O Molecule
- water is made up of billions of molecules, each consisting of 2 hydrogen atoms combined with one oxygen atom, forming H2O
- oxygen has a partial neg charge, hydrogen has a partial pos charge
Hydrogen Bonding
- water molecules are attracted to each other because of these contrasting pos and neg, known as hydrogen bonding
- these bonds are strongest in ice
- explains water’s physical states
High Surface Tension
- another attribute of water = high surface tension
- results when molecules at the surface of liquid have a strong attachment to each other but not to the molecules of air above them
- particularly strong in water because of hydrogen bonding - water molecules pull harder to create a small surface area, also creating an elastic skin on the surface of the water
Capillary Action
- water has the ability to move upward in thin openings/capillaries against the force of gravity within the soil/plants in a process called capillary action
- water molecules pull other water molecules along through hydrogen bonding
- enables plants to transport nutrients from their roots up into their stems/leaves
High Heat Capacity
- water’s specific heat is 1 calorie/gram or 4190 joules/kg
- compared to copper: 0.092 calories/gram or 386 joules/kg
- water would require much more energy to achieve an increase in heat
- this high specific heat occurs because of the significant kinetic energy required to break the hydrogen bonds between the water molecules
Thermal Properties of Water and Its Physical States
Latent Heat
- latent heat is the energy required to change the state of a substance (form or break hydrogen bonds)
- water absorbs and releases latent heat that is stored in molecular bonds
- capability of water to store and release latent heat is important & contributes significantly to atmospheric circulation and helps regulate climate
- explains how water can exist in 3 states (solid/ice, liquid/water, gas/water vapour) as the movement of water from one phase to another occurs when hydrogen bonds are formed, loosened, broken, or tightened
- loosened/broken: energy is applied to molecules and transformed from sensible heat to latent heat which has a net cooling effect
- formed/tightened: energy is extracted from molecules, energy is converted from latent heat to sensible heat, which has a net warming effect
Specific Heat
- specific heat is the energy required to increase the temperature of a substance
WATER PHASES AND LATENT HEAT TRANSFERS:
Liquid Water turns to Ice
- freezing
- more hydrogen bonds develop and tighten
- begins when the water cools to a temp below 4C because the motion of water molecules begins to slow considerably, allowing hydrogen bonds to strengthen
- when the water cools to 0C, motion slows further, more bonds develop and tighten, and ice forms
- exact temp water crystallizes at depends on air pressure, water has to cool more to freeze at higher air pressure because as density increases, increasing amounts of nitrogen/oxygen molecules go into solution
- during freezing, 80 calories of latent heat energy released for every gram of water as the latent heat of freezing
- ice can float on water because it is less dense
Ice turns to Liquid Water
- melting into liquid water, 80 cal of latent heat is absorbed as the latent heat of melting to change 1 gram of ice to 1 gram of water
- heat energy is applied to and absorbed by ice at 0C, the motion of water increases and some hydrogen bonds begin to break
Liquid Water turns to Water Vapour
- vaporization
- process begins at room temperature when added energy causes hydrogen bonds to further loosen, resulting in the liberation of some water molecules to the vapour phase in the process of evaporation
- added heat is called the latent heat of vaporization and = 600 cal per 1 g of water
- when temp reaches 100C, molecular bonds break and all water molecules move into the atmosphere as vapour
Water Vapour to Liquid Water
- condensation
- 600 cal of energy released as the latent heat of condensation
Ice to Vapour
- sublimation
- occurs if temp. of ice rapidly increases from 0C to 100C
- 680 calories of energy known as the latent heat of sublimation (reflects melting + vaporization)
Vapour to Ice
- deposition
- 680 calories of latent heat released (reflects condensation + freezing)
The Hydrosphere and the Hydrologic Cycle
- total water realm of Earth = the hydrosphere
Hydrosphere
- 97.2% = oceans / salt water
- 2.8% = nonoceanic water
Nonoceanic Water
- 2.15% = ice sheets, glaciers
- 0.63% = groundwater
- 0.02% = available freshwater
Available Freshwater
- 0.009% = freshwater lakes
- 0.008% = salt lakes, inland seas
- 0.005% = soil water
- 0.001% = atmosphere
- 0.0001% = rivers, streams
Hydrologic Cycle
- movement of water between the various storage locations
- balanced in the sense that Earth has a finite amount of water, the amount evaporated equals the amount precipitated on a global scale
- variety of local and regional imbalances exist
- sea-level changes due to: eustasy (changes in distribution) or isostasy (subsidence or uplift of continents)
The Global Water Balance
- water flows to the land and ocean surfaces are positive inputs, whereas those leaving are negative
Processes/Mechanism of the Hydrologic Cycle
Movement Toward or Away from Earth’s Surface
- precipitation (of water in all forms)
- evapotranspiration (evaporation - water molecules gain enough energy to become water vapour + transpiration - water transpiring from the pores on plant leaves)
- condensation (opposite of evaporation)
- throughfall (precipitation that makes its way to earth with no interceptions)
- interception (opposite of throughfall, doesn’t make its way directly to earths surface, can evaporate off of the surface it lands on)
- stemflow (when water flows off the surface of interception)
Water at Earth’s Surface and Subsurface
- infiltration (when water breaks the barrier of the surface of the soil)
- percolation (after infiltration, as it moves down through individual soil particles)
- runoff: saturated overland flow (when the soil is slowly fully saturated and water begins to run off), horton overland flow (the intensity of precipitation is greater than the infiltration rate of the soil causing runoff)
- sheet flow (sheets/layers of water flowing over one another after heavy rain, laminar flow)
- channelized flow (turbulent flow)
Soil - Water Balance Concept
- an accounting of water inputs and outputs
- Developed by C.W. Thornthwaite to:
- describe allocation of water
- describe surplus or deficit at a location
- determine timing and quantity of irrigation
- develop climatic classification
Equation:
P - precipitation (moisture supply)
AE - actual evapotranspiration (actual moisture demand)
PE - potential evapotranspiration (moisture demand)
S - surplus (moisture oversupply)
ST - change in soil moisture storage (moisture savings)
D - deficit (moisture shortage)
P = AE + S +/- ST AE = PE - D
Potential Evapotranspiration
- evaporative demand of the atmosphere
- a function of temperature and humidity
- Includes: evaporation from the soil/other surfaces, plus transpiration of water from vegetation
- Measured: evaporimeter, weighing lysimeter, or estimate PE based on mean monthly temperature and day length
Deficit
- PE is satisfied by either: precipitation (monthly) or soil moisture storage (monthly)
- If PE is not met, a deficit (D) occurs
Actual Evapotranspiration
- Difference between PE and D is AE
- example: P= 60mm, PE= 100mm and ST=20… D= 20mm and AE= 80mm
Surplus
- occurs when P is greater than PE and soil moisture storage (ST) is at field capacity
- surplus collects in ponds/puddles, percolates through soil and recharges ground water, or runs off as sheet flow/channelized flow
Issues with this model:
- thornthwaite model assumes that all excess precipitation goes into
soil moisture storage until field capacity is attained, doesn’t consider Horton
overland flow or detained water
Soil Moisture Storage
3 Types of Soil Moisture
- H2O (not available)
- water fully saturated
- infiltrates at surface
- percolates downward in between pore spaces
- draining out the bottom is gravitational water (not available to plant roots) - H2O Available
- capillary and hygroscopic water
- field capacity : occurs when soil is holding the max amount of capillary water - H2O unavailable for plants
- hygroscopic water
- wilting point : occurs when all available capillary water has been used
Soil Porosity and Permeability
- diagram saved
Water Budget Graph
- graphic depiction of water balance
- depicts distribution and use of available water at a given location
- most locations experience seasonal deficits and surpluses
- problem is often timing rather than availability of water
Groundwater & Groundwater Use & Groundwater Pollution
- movement of gravitational water: infiltration and percolation occurring, leading to groundwater
- movement from groundwater systems into streams/other water bodies based on the water level
- ground water moves from higher hydrologic gradient to lower hydrologic gradient
- groundwater recharge happens over millions of years
- cone of depression : change in the location direction of ground water flow where the wells are located
Groundwater Use
- more than 50% of US relies on groundwater
- Volume of available water varies; called specific yield
- Draw down results in a cone of depression, water law
- Groundwater mining occurs when pumping exceeds recharge
and results in (in addition to cone of depression): subsidence due to decreased
pore water pressure, and encroachment of sea water in coastal areas
Groundwater Pollution
- Groundwater pollution categorized according to
the origin of the source
- Non-point source pollution originates over a large
area e.g. herbicide or pesticide application
- Point source pollution originates at a specific site
e.g. hazardous waste dump, contaminant spill, or injection well
Aquifers and Aquiludes
Aquifer
- rock or sedimentary unit of sufficient porosity & permeability is able to store and transport significant
amounts of water
- located above the main water table
- confined aquifer: aquiclude above and below it, puts the aquifer under pressure
Aquiclude - rock or sedimentary unit insufficient porosity and/or permeability does not contain or transport significant amounts of water
- located below the main water table
Water Use
Consumptive
- are uses whee the water is not returned to the water system, at least not in the near future
- typically a reduction in quantity, and also a reduction in the quality when returned to the system
- examples: municipal water uses (in home uses), food processing, irrigation
Non-consumptive
- when the water is removed only temporarily
- does not impact the quantity, but can significantly impact the quality
- withdrawal water and use in industrial processes
- examples: industrial applications, cleaning/processing/washing
Instream Uses
- water is not taken out of the system
- ex. canoeing, fishing, waterskiing
- quantity is not changing
- could be significant impacts on the quality, examples like using a boat in the water
Water Resources Vulnerability Index (1995)
- very few countries that are not facing any vulnerability regarding their water resources
- vulnerability is in regard to the cleanliness and the availability for uses
Karst Landforms and Landscapes
Caves and Caverns
- Karst = type of landform or landscape that develops in an area where the bedrock rock is limestone or Dolomite or soluble sedimentary rock
- Karst topography
includes caves,
sinkholes, and
other soluble rock
features - Limestone
dissolves easily
through the
chemical
weathering
process of
carbonation - limestone soluble in water
Cave and Cavern Evolution
- Stage One: Begins when water table is high and carbonation
concentrates in limestone just
below
- Stage Two: Stream cuts a valley into the rock, lowering the water table, and groundwater cuts
channels and caverns into the rock
- Stage Three: The stream
continues to downcut and water table lowers further, revealing caves and caverns
Unique landforms associated with karst landscapes:
- large caves in highly developed areas
- features within caves exist
Geography of the Lithosphere
- To this point, we have focused on systems operating within the atmosphere and hydrosphere
- Now we turn our attention to the lithosphere and
systems operating at or beneath Earth’s surface:
exogenic systems
– at earths surface
endogenic systems - below earths surface
Geography of the Lithosphere
- To this point, we have focused on systems operating within the atmosphere and hydrosphere
- Now we turn our attention to the lithosphere and
systems operating at or beneath Earth’s surface:
exogenic systems
– at earths surface
endogenic systems
- below earths surface
Earth’s internal energy
Two sources of energy drive
endogenic systems:
1. residual
2. radioactive
- radioactive decay of unstable isotopes
- locally within the earths interior, concentrations of unstable isotopes that decay and release heat energy
- ex. in yellow stone area, concentration of heat energy in earths interior, hotspot, caused by unstable isotopes
3. friction heat energy
- only a MINOR source
- caused by one lithospheric plate moving past another
- enough friction to create a minor amount of heat energy
History of Earth History
Creationist interpretations:
- Neptunism
- water
- theory that all rocks are of sedimentary origin and precipitated at the bottom of ocean basins and shaped by running water, related to biblical flooding
- Catastrophism
- catastrophic events
- the idea that earth geography and geology are primary the result of catastrophic events (Biblical flooding)
- shaping and reshaping landforms and landscapes
- most earth surface features had been formed by catastrophic events over short periods of time
Scientific Interpretations of Earths History ::
Plutonism - Earth's interior is molten, all rocks of volcanic origin, James Hutton (1795), Theory of the Earth
Uniformitarianism (gradualism)
- “the present is the key to the past” CATCHPHRASE, the key to understanding the past, is to look at processes/mechanisms today, nothing has changed by natural laws and principles, explains 99% of todays geography
- same processes operating to shape the Earth today
have been operating throughout geologic time, James Hutton (1795), Theory of the Earth; Charles
Lyell (1830), Principles of Geology
- uniformitarianism/ gradualism - the earth is shaped over thousands/millions of years by the processes
- different processes operating today include continental scale glaciation in mid latitudes
- this theory works very well, with only few limited exceptions
how old is the earth
- the universe : 13.8 billion years
- the milky-way way : 13.6 billions years ago
- our sun - 4.5 billion years ago
- earth - 4.6 billion years ago
