Water Properties Flashcards
is water polar or non-polar?
polar
why is water polar?
asymmetry of hydrogen atoms
what are the benefits to water being polar?
- good solvent
- high heat capacity -> 1 calories to raise 1g of water by 1C
- high heat of fusion
- high heat of vaporization
are all the elements in seawater not constant?
no they are all in constant proportions in all oceans
what elements are used to measure salinity by chlorinity?
chlorine
sodium
what is used to measure salinity by conductivity?
elements make saltwater conductive
what is salinity?
of grams of elements in 1000g of water
what makes salinity vary?
varies by latitude due to evaporation and precipitation
- more locally by sea ice formation and river input
what are thermoclines?
vertical temperature
- gradient in temp
what are haloclines?
salinity gradients
what kind of water is dense and sinks?
cold saline water
how much of Earth is covered by water?
71%
what % of oceans are deeper than 2000m?
84
what is the deepest point in oceans?
11 000m - Mariana Trench
- Challenger Deep
what are marginal seas?
semi-enclosed regions affected by local climate
- shallow
what are the regions of the oceans?
continental shelf
canyons -> channels sediment movement downwards
abyssal plain -> basic ocean floor
mid-oceanic ridges
shelf-slope break
what is the ocean floor made of?
plates
are tectonic plates static?
no - constantly moving
what forms at ridges?
new crust
can the seafloor be dated?
yes
what shows polar reversals?
magnetic stripes
what is the kind of evidence that suggests that continents were once united?
fossils
which hemispheres has more water?
southern - 80% compared to north which has 61
what is the Deepsea Challenger?
Cameron got to the bottom of Trench and back in 2h37min
is the rate of descent or ascent slower during Deepsea?
descent bc of the pressure under water
what are examples of Marginal Seas?
Strait of Georgia
Gulf of Mexico
Mediterranean Sea
what are marginal seas affected by?
- regional climate -> microclimate
- precipitation-evaporation balance -> salinity affected
- river input of fresh water and dissolved solids -> Hudons’ Bay closer to river is less salty
- limited exchange with open ocean
- geological history -> Salish Sea in Georgia Depression formed by collision of plates
what is seafloor spreading?
oceanic crust is formed at ridges, moved laterally and destroyed by subduction, which forms trenches
what is a good example of seafloor spreading?
hotspots
- regions where the hot mantle rises in stationary plume forming volcanoes
where is a hotspot located?
Hawaii
- islands are formed by seafloor moving over hotspot
- chain of volcanic islands
- when crust moves then little volcanoes form
what causes continental drift?
continents are embedded in ocean crust so when crust moves then continents move
who was the first to figure out theory of continental drift?
Alfred Wegener
what are the 4 evidences for continental drift?
- fossils
- seafloor mapping/radiometric dating -> seafloor younger than continental crust
- magnetic anomalies -> magnetic stripes on ocean floor near spreading ridges show movement of oceanic crust -> Earth’s magnetic field switches so polarity becomes opposite
what is the strongest bond?
covalent - b/w oxygen and hydrogen and between water and other ions
what is a weak bond?
hydrogen - between water molecules
- gives sticky properties
- creates surface tension
what does polarity allow for?
ability to form bonds with other ions
does it take a lot of energy to break H bonds?
yes
- lots of energy to heat up and lose energy
- water has a large thermal buffer capacity and acts like a climate buffer
- energy transported by water in ocean currents is large -> water from the S brings heat to the N (water holds onto heat)
t or f: water has a low latent heat of fusion
f- highest of all common materials
does water hold onto heat?
no
- heats and cools faster than adjacent water bodies -> northern land masses do not necessarily experience Arctic climates bc of warm water currents
- water transports heat and cold over vast distances -> water from Artic can affect Antarctic waters
does deep water have a wide range of temperature?
no 2-4 C
does the surface of deep water have a large latitudinal range?
large -1.9 to 40C
describe shallow temperate ocean?
Hudsons Bay
- thermocline is less drastic in the summer bc water mixes
- in winter the water temp is consisten bc the surface is consistent temp
why are there latitudinal temperature differences?
- latitudinal gradient of solar heating +
- geothermal heating +
- internal friction +
- water vapor condensation +
- back radiation off surface -
- convection of heat to atmosphere -
- evaporation -
what controls salinity?
adds salt by evaporation and sea-ice formation
removes salt by precipitation and river runoff
what is chlorinity?
grams of chlorine per l of seawater
what does salinity =?
1.81 x chlorinity (2 times)
how to measure chlorinity?
- chemical titration
- conductivity -> most reliable, changes based on temp
- index of refraction -> more stuff in ocean them more stuff for light to refract off of
what is used to measure salinity in seawater?
CTD- conduction, temp, depth
- tests how conductivity varies with temp and depth
- conductivity is a measure of salts in water
- main salt is chloride
what is Principle of Constant Element Ratios?
Forchhammer’s Principle
- ratio b/w many major elements are constant all over the oceans even though salinity varies
- residence time of Na, Cl and Sr is on the order of millions of years -> salts come from river input to the oceans over millions of years
- mixing time of water is on order of thousands of years
- ocean is mixed well
what occurs at mid-latitudes?
excess of evaporation over precipitation
what occurs at the equator?
excess of precipitation over evaporation at equator
t or f: the maximum density of seawater is at 4C?
F
- density influenced by salt and temp
when does density increase?
with increasing salinity and decreasing temp
what does temp and salinity give rise to?
vertical gradients of density
describe shallow water
warm - more saline - less dense
describe deep water
cold - less saline - more dense
does saltwater freeze at a colder temp than freshwater?
yes
what is brinicle?
saltwater sinks, seawater freezes and grows downward, touches the seafloor and kills everything bc it freezes
