JMU Geol 211 Exam 2
areas of heat gain and heat loss on earth
tropical and subtropical areas of earth have a net surplus of heath, the polar regions have a deficit of heat
solar energy spectrum
ultraviolet, visible, infrared light. The amount of solar energy reaching earth varies markedly by latitude and by season
response times of various climate system components
1. atmosphere: hours to weeks - daily heating and cooling, gradual buildup of heat wave 2. land surface: hours to months - daily hearing of upper ground surface, midwinter freezing and thawing 3. ocean surface - days to months: afternoon heating of upper few feet, warmest beach temperatures late in summer 4. vegetation - hours to decades/centuries: slow growth of trees to maturity 5. sea ice - weeks to years: late-winter maximum extent, historical changes near Iceland 6. mountain glaciers - 10-100 years: widespread glacier retreat in 20th century 7. deep ocean - 100-1500 years: time to replace world's deep water 8. ice sheets - 100-10,000 years: advances/retreats of ice sheet margins, growth/decay of entire ice sheet
average ocean temperature
17 degrees C. Highest recorded temp is 36 degrees C (persian gulf) and coldest is -2 degrees C. Range = 38 degrees C
cations
Ca2+, Mg2+, Na+, K+. these come from the weathering of the rocks of earth's crust. Silicates (ex. hydrolysis of feldspar), non-silicates (ex. dissolution of limestone)
anions
Cl-, SO42-, HCO3-. these come from the outgassing of the mantel by volcanism. major volcanic gases: HCl, SO2. SO#, CO2. each is highly soluble in H2O, and upon dissolution in water, each forms H+ ions, and the above anions
El Nino, La Nina, and the Southern Oscillation
El Nino: Spanish for the child, specifically the Christ Child. Term is used by fisherman along the coast of Ecaduor and Peru to refer to warm, nutrient-poor, ocean waters that typically appear around Christmas and remain for several months, typically bringing heavy rains and flooding and poor fishing conditions. La Nina: Spanish for the girl child, refers to waters along the Pacific coast of South America that are cooler than normal. Southern Oscillation: recent discovery, refers to an oscillation in the surface air pressure (atmospheric mass) between the southeastern tropical Pacific and the Australian-Indonesian regions. When the waters of the eastern Pacific are abnormally warm (an El Nino event) sea level pressure drops in the eastern Pacific and rises in the west. The reduction in the pressure gradient is accompanied by a weakening of the low-altitude easterly trades
two examples of heat transfer by oceanic and atmospheric currents
Gulf stream, Atlantic storms
sediments
Loose materials such as rock fragments, mineral grains, and bits of shell that have been moved by wind, water, ice, or gravity - the depth and composition of marine sediments tell us of relatively recent events in the ocean basin. Because marine sediments are usually subducted along with the seabed on which they lie, the oldest sediments are relatively young - rarely older than 180 million years
pelagic sediments
Sediments of the slope, rise, and deep-ocean floor that originate in the ocean.
temperature
a measure of the hotness of an object, related to the average kinetic energy per molecule in the object, measured in degrees Celsius, degrees Fahrenheit, or Kelvins
evaporite rocks
anhydrite (CaSO4) cement in limestone from another great petroleum reservoir in Saudi Arabia. Note the loss of pore space because of the anhydrite cement
circulation in the ocean
at various times throughout the Paleozoic, intense evaporation occurred in some restricted basins, leading to accumulation of thick evaporite sequences.
season temp in ocean
average change in temp between seasons in the ocean: 2 C in tropics, 5-8 C in middle latitudes, and 2-4 C in polar latitudes. the change in temperatures between seasons on land in contrast, can exceed 50 C
what is the origin of the ocean's salts (= dissolved solids)?
cations (weathering of rock) and anions (outgassing of mantle)
condensation
change of phase from gaseous to liquid
sublimation
change of phase from solid to gaseous, skipping the liquid phase
melting
change of phase from solid to liquid
neritic sediments
continental shelf sediments
the ocean is densely stratified
dense and cold salty water underlies less dense water and fresher water. Light is quickly extinguished by passage through water. Sound is not. Light and sound can be refracted (bent) by passage between water masses whose physical characteristics differ
circulation of the atmosphere
earth's ocean and atmosphere are unevenly heated by the sun - more solar energy is absorbed near the equator than near the poles. The atmosphere circulates in response to this difference in heating. Moving objects tend to move to the right of their initial course in the northern hemisphere (and to the left in the southern hemisphere). This tendency is called the Coriolis effect. The atmosphere circulates in six large circuits (three in each hemisphere). Storms can form between two air masses (frontal storms) or within one air mass (tropical cyclones)
What happens when an El Nino even occurs
east-to-west winds (trade winds) in the Pacific Ocean weaken, and may even change direction. Cold waters fail to rise from the deep ocean (an upwelling) off the coast of South America. As a result, sea temperatures in the Eastern Pacific typically are up to 8 degrees warmer than normal. Dry, high pressure air masses that typically occur in the eastern Pacific are replaced by humid, low pressure air masses that are usually located over the western Pacific. This results in normally dry coastal areas along the eastern Pacific to receive more precipitation than normal, and normally rainy areas of the western Pacific experience drier than normal conditions. "normal" weather patterns around the world are disrupted (the Pacific is the largest feature on earth, so what happens there affects the entire world)
terriegnous sediment
erosion of land, volcanic eruptions, windblown dust. ex: quartz beach, sand, estuarine muds and silts. covers 45% of ocean floor. Generated from the weathering and erosion of earth's landmasses. Classified by size (based on the diameter of the grain). Rivers deliver the majority of terrigenous sediments to the oceans (in descending order, rivers, glaciers (move sediment like a bulldozer moves dirt) (waves, currents, and tides slowly but steadily wear away the bluffs, headlands, and cliffs along coasts) - when lithified, these sediments form conglomerates, sandstones, and mudstones) and ice sheets, wind-blown dust, coastal erosion, volcanic debris, and groundwater). The highest mountains are being eroded the fastest, generating the greatest amount of sediment
why oceanic circulation in the basins became restricted, leading to increased evaporation
evaporites are forming today in the United Arab Emirates on the Trucial Coast of the Persian Gulf, a basin with restricted circulation and elevated salinities
cosmogenous sediment
extraterrestrial glassy tektites, meteorites, and dust. ex: tektites (glassy spheres), magnetic spherules. covers 0% of ocean floor. Also include microtektites.
average land temp
highest recorded: 58 degrees C (136 F), lowest recorded = -88 degrees C (-126 F). Range = 130 degrees C.
what is the importance of chalk?
it is indisputable evidence that an area was once covered by the ocean, and that the deposition of marine sediments was widespread
carbonate rocks
limestone: made of calcite (calcium carbonate), chemical and biogenic rock. Dolomite - made of dolomote (calcium magnesium carbonate), uncommon in modern rocks, common in ancient rocks, note the petroleum in the pore spaces. Carbonate sediments: skeletal particles (ex. shells) are very common in many shallow marine environments. Require warm, clear, shallow (sunlit), and oxygenated waters . Oolites: nearly spherical sediment, produced in shallow water, formed by rolling around in the waves and currents
absolute zero
lowest possible temperature: the temperature at which all particles have their minimum kinetic energy
importance of pH
marine organisms that have shells or other skeletal components made of calcium carbonate would dissolve if seawater were acidic. a basic pH is necessary for the formation of many complex organic compounds. Buffering: the process of maintaining the pH, minimizing sudden changes in pH
global atmospheric circulation
net result of global atmospheric circulation: heat is carried from the tropics and delivered to temperate regions, which are also on the receiving end of cold polar air and are thus a "mixing zone" for earth's temperature extremes
circulation of the ocean
ocean circulation is driven by winds and by differences in water density. Along with the winds, ocean currents distribute tropical heat worldwide. Surface currents are wind-driven movements of water at or near the ocean's surface. Thermophaline currents are slow, deep currents that affect the vast bulk of seawater beneath the pycnocline. Surface currents move in circular circuits - gyres - around the peripheries of major ocean basins. El Nino and La Nina affect ocean and atmosphere. El Nino is an exception to normla wind and current flow
average salinity values (parts per thousand)
ocean: 35. These are seven ions (chloride, sodium, sulfate, magnesium, calcium, potassium, bicarbonate) total 99.7% of all dissolved solids in seawater
biogenous sediment
organic - hard parts of marine organisms. ex: calcareous and siliceous oozes. covers 55% of ocean floor. Biogenous sediments in the deep ocean are known as oozes, and are primarily either calcareous or siliceous, or a mix of the two. The most important calcareous oozes are made of the tests (shells) of organisms called foraminifera (forams - abundant in the calcaerous oozes of the seafloor) and coccoliths (are tiny but so abundant that when "blooms" of them occur, they can be seen from orbiting satellites, make up chalk deposits of the world) (micropscopic organisms make up much of the calcareous oozes of the ocean floor). The most important siliceous oozes are made up the tests of organisms called diatoms and radiolarians (like radiolarians, diatoms come in many shapes). Coarser grained calcareous sediments are usually shell fragments and pieces - when lithified, these sediments form fossiliferous limestones)
pH scale
pH = -log[H+]
hydrogenous (chemical) sediment
precipitation of minerals from seawater. ex: manganese nodules, phosphorotes. covers less than 1% of ocean floor. The principle hydrogenous sediments are evaporites and manganese nodules.
specific heat capacity
quantity of heat per unit of mass required to raise the temperature of a substance by 1 degree Celsius
boiling
rapid evaporation that takes place within a liquid as well as its surface
seawater properties
salinity - amount of dissolved solids plus dissolved gases (in grams) in 1000 grams of seater solvent - a liquid that has one or more substances dissolved in it
heat is not the same as temperature
temperature is an object's response to an input (or removal) of heat. Not all substances respond in the same way. Water resists rising in temperature as heat is added. Water gives off heat when it freezes and absorbs heat as it thaws. These properties of liquid water moderate earth's surface temperatures
what are the most abundant sediments
terrigenous (from land and most abundant) and biogenous (from once-living things)
sediments of the marine environment
terrigenous, biogenous, hydrogenous, cosmogenous
energy
the ability to do work (actually a characteristic of energy than a definition). Energy is the property/characteristic/trait of matter that makes things happen; in the case of potential (stored) energy, it has the potential to make things happen. For example, changes in shape, volume, chemical composition, pressure, temperature, density, and phase. Energy cannot be created or destroyed (law of conservation of energy). The change in internal enegy of a system equals the heat added to the system minus the work done by the system (1st law of thermodyanics). In all systems and all transformations of energy, some of the energy is lost as heat, and cannot be used to do work (2nd law of thermodynamics). Without energy, nothing would ever happen; nothing would ever change.
evaporation
the change of phase from liquid to gaseous
physical and chemical aspects of water
the hydrologic cycle
thermal energy (internal energy)
the total energy (kinetic plus potential) of the particles that make up a substance
heat
thermal energy that flows from an object at higher temperature to one at a lower temperature, commonly measured in calories or joules
why are there so little SiO2(aq), Ca2+, and HCO3- in the oceans?
these are the chemical building blocks of skeletal materials for many marine organisms
insolation
total amount of solar radiation energy received on a given surface area of earth during a given time (summer = more insolation, winter = less insolation)
calorie
unit of thermal energy, or heat. one calorie is the thermal energy required to raise the temperature 1 gram of water 1 degree Celsius. (1 cal = 4.184 J). one Calorie (C) is equal to 1000 calories and is the unit used in describing the energy available from food
heat capacity (cal/g/degrees Celsius) of important oceanic substances
water's heat capacity: 1.00. land surfaces warm up and cool down daily, and seasonally. Oceans warm up and cool down seasonally. Corollary: why are the hottest days of summer usually weeks after the "longest" day of the year, and the coldest days of winter usually weeks after the "shortest" day of the year?
do gases dissolve in seawater?
yes - cold water can hold more gas in solution than warm water. The ocean is a vast reservoir of carbon. The dynamics of carbon exchange between ocean and atmosphere affect earth's climate. The ocean's acid-base (pH) balance varies with depth and dissolved components. Carbonate chemistry serves to moderate (buffer) wide swings in oceanic pH
Is water a powerful solvent?
yes - the concentration of dissolved inorganic solids in water is its salinity. Though salinity may vary with location, the ratio of dissolved solids in seawater is constant
