The Physical The Physical

Properties of Properties of

WaterWater

An Introduction to the World’s Oceans Sverdrup et al. - Chapter Five - 8th Ed.

Table 5.1 topTable 5.1 top

Table 5.1 bottomTable 5.1 bottom

The Water MoleculeThe Water Molecule

HH22O: two hydrogen atoms and one O: two hydrogen atoms and one

oxygen atomoxygen atom

Covalent bondsCovalent bonds

Polar moleculePolar molecule

Hydrogen bondsHydrogen bonds

Temperature and HeatTemperature and Heat

Molecules in motion: solids, liquids & gases Molecules in motion: solids, liquids & gases

– increasingly disorganizedincreasingly disorganized

Average atomic or molecular kinetic energy Average atomic or molecular kinetic energy

measured by temperature in degrees of three measured by temperature in degrees of three

scalesscales

– Fahrenheit (Fahrenheit ( o o F), Celsius (F), Celsius (

o o C) or Kelvin (K)C) or Kelvin (K)

32 32 oo F = 0 F = 0 oo C = 273.15 K ( freezing point of water ) C = 273.15 K ( freezing point of water )

212 212 oo F = 100 F = 100 oo C = 373.15 K ( boiling point of water ) C = 373.15 K ( boiling point of water )

0 K = absolute zero0 K = absolute zero

Heat: measure of the total amount ofHeat: measure of the total amount of kinetic energy kinetic energy

Changes of StateChanges of State Three states of water: Three states of water:

solid, liquid and solid, liquid and gasgas– dew pointdew point

Changes of stateChanges of state– Hydrogen bondsHydrogen bonds

– Latent heat of fusionLatent heat of fusion 80 calories / g- 80 calories / g- oo C C

– Latent heat of vaporizationLatent heat of vaporization 540 calories / g- 540 calories / g- oo C C

– Pressure dependencePressure dependence Depressed freezing/boilingDepressed freezing/boiling

– Sublimation – ice to vaporSublimation – ice to vapor

– Salinity effectsSalinity effects

Table 5.2Table 5.2

Heat CapacityHeat Capacity Heat capacity: Heat capacity:

quantity of heat quantity of heat required to produce required to produce a unit change in a unit change in temperaturetemperature

Hydrogen bonds Hydrogen bonds and high heat and high heat capacity of watercapacity of water

Stability of Earth’s Stability of Earth’s temperaturetemperature– High heat capacityHigh heat capacity– High latent heat of High latent heat of

fusionfusion– High latent heat of High latent heat of

vaporizationvaporization

Cohesion, Surface Cohesion, Surface Tension, Tension,

and Viscosityand Viscosity

Hydrogen bonds hold water togetherHydrogen bonds hold water together– CohesionCohesion

– Surface tension: measure of how Surface tension: measure of how difficult it is to stretch or penetrate the difficult it is to stretch or penetrate the surface of a liquidsurface of a liquid

Viscosity: resistance to motion or Viscosity: resistance to motion or

internal frictioninternal friction Effects of temperature on viscosityEffects of temperature on viscosity

DensityDensity The effect of pressure The effect of pressure

– Water is nearly incompressibleWater is nearly incompressible

– Pressure increases with depthPressure increases with depth

– Density increases with depthDensity increases with depth

The effect of temperatureThe effect of temperature– Density decreases temperatureDensity decreases temperature

– Density of iceDensity of ice

– Density of moist air Density of moist air

The effect of saltThe effect of salt– Density increases with salinityDensity increases with salinity

– Combined effect of temperature and salinity near the Combined effect of temperature and salinity near the freezing pointfreezing point

Table 5.4Table 5.4

Dissolving AbilityDissolving Ability Water is the “universal solvent” Water is the “universal solvent” Polar nature of water molecules Polar nature of water molecules

Transmission of EnergyTransmission of Energy Heat Heat

– ConductionConduction– Convection Convection – RadiationRadiation

LightLight– Electromagnetic Electromagnetic

radiation radiation – Absorption, scattering, Absorption, scattering,

and reflectionand reflection– Attenuation and Beer’s Attenuation and Beer’s

LawLaw– Attenuation and Attenuation and

wavelength of lightwavelength of light SoundSound

– Speed of sound in Speed of sound in seawaterseawater

– DissipationDissipation– Sound shadow zonesSound shadow zones– Sofar channelSofar channel

Light & SoundLight & Sound Scattering & absorption (attenuated)Scattering & absorption (attenuated)

frequency dependentfrequency dependent

Photic & aphotic zonesPhotic & aphotic zones Refraction Refraction Sound also scattered and absorbed Sound also scattered and absorbed

(attenuated)(attenuated) frequency dependentfrequency dependent

Velocity increases with salinity, P & T.Velocity increases with salinity, P & T. 1500 m/sec in H1500 m/sec in H22O vs. 334 m/sec in air @ sea levelO vs. 334 m/sec in air @ sea level

Speed of sound = (axial modulus/density) Speed of sound = (axial modulus/density) ½½

Deep Scattering Layer & other “organism” affects Deep Scattering Layer & other “organism” affects The SOFAR layer (The SOFAR layer (sosound und ffixing and ixing and rranging)anging) SONAR (SONAR (sosound und nanavigation and vigation and rranging)anging)

Fig. 5.9Fig. 5.9Attenuation of “Light”Attenuation of “Light”• AbsorbedAbsorbed

• By waterBy water• By organisms - By organisms -

photosynthesisphotosynthesis

• ScatteredScattered• ReflectedReflected

Table 5.6Table 5.6

Fig. 5.10Fig. 5.10RefractioRefraction of n of LightLight

Secchi DiskSecchi Disk

MMarine arine OOptical ptical BBuouoyy

Fig. 5.13Fig. 5.13Travel

time vs. depth

d = ½ v t

Fig. 5.14Fig. 5.14

Precision

Depth Finder

Acoustic Thermometry of Ocean Acoustic Thermometry of Ocean ClimateClimate

Sound speed Sound speed

and travel time: and travel time:

function of function of

temperaturetemperature

Low frequency Low frequency

sound pulses sound pulses

can measure can measure

global warmingglobal warming

Effects on Effects on

marine marine

mammalsmammals

Ice and FogIce and Fog Sea iceSea ice

– Formed by low air and water temperaturesFormed by low air and water temperatures– Freezing seawaterFreezing seawater– Salt water in ice escapes over timeSalt water in ice escapes over time

IcebergsIcebergs– Formed by glaciers on landFormed by glaciers on land– Iceberg activity may be due to global warming, Iceberg activity may be due to global warming,

driving an increased rate of meltingdriving an increased rate of melting FogFog

– Condensation of moisture forms cloudsCondensation of moisture forms clouds– Three types of fogThree types of fog

Advective fog—warm, water-saturated air passes Advective fog—warm, water-saturated air passes over cold waterover cold water

Sea smoke—dry, cold air moves over warm waterSea smoke—dry, cold air moves over warm water Radiative fog—warm, moist air cools at nightRadiative fog—warm, moist air cools at night

Fig. 5.18c,dFig. 5.18c,d

Green IcebergsGreen Icebergs Color of icebergs Color of icebergs

normally blue to normally blue to

whitewhite

Green ice Green ice

contains contains

dissolved organic dissolved organic

material from material from

seawaterseawater

Formed by Formed by

freezing seawater freezing seawater

under ice shelvesunder ice shelves

The EndThe End