PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Temperature, Heat, Heat Capacity, Calories, etc.Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Regulating the Major Constituents in seawaterSlide 33Slide 34Slide 35SeawaterSlide 37Slide 38Chapter 6/7Chapter 6/7Water, Ocean Structure & Water, Ocean Structure & ChemestryChemestry22http://www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html33http://arctic.atmos.uiuc.edu/cryosphere/4455Hydrogen bonds form when the positive end of one water molecule bonds to the negative end of another water molecule.Two important properties of water molecules:Cohesion – the ability of water molecules to stick to each other, creating surface tension.Adhesion – the tendency of water molecules to stick to other substancesHydrogen Bonds66Temperature, Heat, Heat Capacity, Calories, etc.Temperature•Measure of av. kinetic energy (motion) of molecules (KE=1/2mv2)•unit is degrees C, F or K (Kelvin)Heat•Measure of the total kinetic energy of the molecules in a substance•Unit is the calorie* Heat Capacity = is a measure of the heat required to raise the temperature of 1g of a substance by 1C.* Calorie = amount of heat to raise temperature of 1 gram of pure water by 1°C (from 14.5 °C to 15.5 °C)* Latent Heat77Not All Substances Have the Same Heat CapacityWater has a very high heat capacity, which means it resists changing temperature when heat is added or removed – large thermal inertia88Remember from Chapter 3? Density is a key concept for understanding the structure of Earth – differences in density lead to stratification (layers). Density measures the mass per unit volume of a substance.Density = _Mass_ VolumeDensity is expressed as grams per cubic centimeter.(pure) Water has a density of 1 g/cm3Granite Rock is about 2.7 times more densejust about everything in this course!Temperature affects water’s density99The relationship of density and temperature for pure water.Note that points C and D both represent 0°C (32°F) but different densities and thus different states of water. Ice floats because the density of ice is lower than the density of liquid water.1010Water Becomes Less Dense When It FreezesThe space taken by 24 water molecules in the solid lattice could be occupied by 27 water molecules in liquid state, so water expands about 9% as the crystal forms. Because molecules of liquid water are packed less efficiently, ice is less dense than liquid water and floats.1111Changes of State-due to addition or loss of heat (breaks H bonds)The amount of energy required to break the bonds is termed the latent heat of vaporization. Water has the highest latent heat of vaporization of any known substance.1212Things to remember: 1. Can have liquid water at 0°C and below (supercooled water) 2. Can change directly solid to gas - sublimation3. Can boil water at temperature below 100°C (if pressure decreases as when at the top of a high mountain)4. Evaporation removes heat from Earth’s surface (it is a cooling mechanism)5. Condensation in atmosphere releases heat that will drive Earth’s weather cycle1313Dissolved salts in water(a) raise T (temperature) of boiling point(b) lower T of freezing point(a) not so important to oceanography but(b) is, as T around 0°C are common overmany areas of the oceansfreezing point of seawater ~ -2°C (-1.91 °C)The effect of salt on water’s properties:1414•The ability of a substance to take in or give up a certain amount of heat and undergo small or large changes in temperature•Water has high heat capacity = 1 cal/g/˚C•Water can gain or lose large quantities of heat without large changes in temperature•Salt does not significantly change water’s heat capacity: heat capacity of seawater = 0.96 cal/g/˚C (4% change)Heat Capacity1515•density = mass per unit volume•measured in grams per cubic centimetersdensity of pure water = 1 g/cm3(determined at ~ 4°C)•density increases as temperature drops to 4°C and then decreases as temperature goes to 0°C•ice is less dense than water•salt increases water’s densitydensity of sea water > density of pure water~ 1.03 g/cm3 at 4°C Density1616http://www.ospo.noaa.gov/Products/ocean/sst/contour/index.html1717•Water nearly incompressible•P increases by 14.7lb/in2 (1 Atmosphere) for every 10 m increase in depth of sea•1 cm3 will lose 1.7% of its volume at 4000m•Thus, sea level is 37 m lower due to compression!Pressure1818San FranciscoNorfolkTemperature (°F)San FranciscoNorfolkTemperature (°C)Surface Water Moderates Global Temperature1919Tropic of CancerTropic of CancerEquatorEquatorTropic of CapricornTropic of CapricornSalinitySalinityTemperatureTemperatureLatitudeNorthSouthOcean-Surface Conditions Depend on Latitude, Temperature, and Salinity2020Table 6-3, p. 1662121Fig. 6-16, p. 168Sea-surface average salinities in parts per thousand (‰).Sea-surface temperatures during Northern Hemisphere summer2222Fig. 6-17, p. 169The Ocean Is Stratified by Densitytwo samples of water can have the same density at different combinations of temperature and salinity!2323The Ocean Is Stratified into Three Density Zones by Temperature and Salinitya.The surface zone or surface layer or mixed layerb.The pycnocline, or thermocline or haloclinec.The deep ocean (~ 80% of the ocean is below the surface zone24245 10 15 20 25PolarTropical2,000Temperate1,0004,0006,0002,000Depth (m)8,000Depth (ft)3,00010,00040 50 60 70Temperature (°F)Temperature (°C)Typical temperature profiles at polar, tropical, and middle (temperate) latitudes. Note that polar waters lack a thermocline.2525Sound and light in Seawater• Sound and light both travel in waves• Refraction is the bending of waves, which occurs when waves travel from one medium to another • Refraction Can Bend the Paths of Light and Sound through Water• Light may be absorbed, scattered, reflected, refracted and attenuated (decrease in intensity over distance)• Sunlight does not travel well in the ocean. Scattering and absorption weaken light2626•Form of electromagnetic radiation•Seawater transmits visible portion of the electromagnetic spectrum (water transmits blue light more efficiently than red)•60% is absorbed by 1 m depth•80% absorbed by 10 m depth•No light penetration below 1000 m•Shorter