The properties of water, currents and tides Flashcards
(25 cards)
outline the structure of a water molecule
a negatively charged oxygen atom and 2 positively charged hydrogen atoms form a polar water molecule with electric attractions called hydrogen bonds
outline how evaporation occurs
when molecules move fast enough it breaks free from all the hydrogen bonds and escapes from the liquid phase into the gaseous phase
why is ice less dense than water
ice is less dense than water as the hydrogen bonds lock the water molecule into a fixed 3D lattice
outline the property of heat capacity in regards to water and organisms in the water
the ability to absorb lots of heat for a with only a small increase in temp means the temp stays relatively stable so marine organisms aren’t subject to rapid changes in temp
define heat capacity
the amount of heat needed to raise a substances temperature
what is salinity
the total amount of dissolved salt in water measured in ppt
how is salinity measured
via the conductivity of sea water, the more ions from the more salt mean electricity is passed through at a faster rate
what determines the density of sea water
the temperature and salinity- water becomes more dense as it gets saltier and colder
temperature is the main controller of seawater density
what are the most important gases in the ocean
oxygen
carbon dioxide
nitrogen
what happens to sea water as temp and salinity increase
concentration of oxygen decreases
why is co2 more soluble than oxygen
it reacts chemically when dissolved in water= the carbonate/bicarbonate buffer system
outline how different wavelengths of light are absorbed by the ocean
shorter wavelengths of light are transmitted better so red is absorbed first and blue/green absorbed last
what is the maximum depth light can penetrate the ocean
1000m
what is the relationship between hydrostatic pressure and depth
it increases linearly
what drives surface ocean currents
heat energy from the sun which causes winds
what is the coriolis effect
the deflection of large scale motions such as winds and currents to the right in the northern hemisphere and to the left in the southern hemisphere
= instead of moving in the same direction as the wind, water moves at an angle of 45 degrees to the wind
what are gyres
the result of wind driven surface currents forming a large, circular system called a gyre
where do warm western currents move to
carry large amounts of solar heat from the equator to higher latitudes and cold currents flow in the opposite direction to the eastern side
what influences currents on the continental shelf
the seabed
shape of coastline
tides
what are the different layers in the ocean
1) surface layer = 100-200m
2) intermediate layer= 1000-1500m
3) deep layer= more than 1500m
4) bottom layer = contact with the seabed
what is a permanent/main thermocline
a transition zone between warm surface water and cold water below
what is a seasonal thermocline
formed in the temperate and polar latitudes in the spring and summer where the upper part of the surface layer is heated by the sun and then there is a sharp transition to cooler water below
the zone disappears when weather cools
what are the main locations where water becomes dense enough to reach the bottom
- Atlantic ocean
- south of Greenland
- north of Antarctica
define fetch
the span of open water over which wind blows. the larger the fetch the larger the size of waves
