GEOSC 040 Midterm
Terms in this set (51)
what is the goldilocks principle as applied to earth and the oceans?
-earth has just the right position in the solar system- not too close to the sun and not too far away
- when it was forming, earth had just the right mass, large enough to retain water vapor
which is greater - the average depth of the ocean or the average elevation of the continents?
the average depth of the ocean is 4 times greater
why do we say there is one world ocean?
we say there is one world ocean because all of the oceans are "connected"
Over time, does water from the Atlantic and Pacific Oceans mix with waters from the Baltic and Mediterranean seas?
yes, due to ocean currents
surface water on earth mostly likely came from where?
from the deep ocean, rain, runoff and other sources
how is ocean deep water different from shallow water?
it has different salinity, temperature, chemical composition, and density. Deep water is colder, saltier and therefore, denser than surface water.
why is water a polar molecule?
-Due to the angular shape of the water molecules.
-because it has an unequal charge distribution
-bonding of oxygen to hydrogen
-bonds are constantly breaking and reforming
What properties of water derive from its polar nature?
Cohesion, adhesion, the blue "tint" of water, very high heat capacity, liquid at room temperature, and solid state (ice) less dense than in liquid form.
What did Rachel Carson suggest about how ocean chemistry may have changed over geologic time (millions of years)?
She suggested that ocean chemistry may have changed over the geologic time due to rain and other factors which weather the continents, bring run-off and other sources of water water back to the ocean. Also, pollution has a factor in the chemistry of the oceans. With these factors, came new chemicals changing the composition of the ocean.
What did Rachel Carson think about the connections between river chemistry and ocean chemistry?
She believed that rivers deliver dissolved rock ( including elements such as Na, Ca and Cl) to the world ocean, which would cause changes in ocean chemistry through time.
What affect does photosynthesis have on the concentrations of CO2 and O2 in seawater?
Because plants and plantlike organisms require carbon dioxide for photosynthesis and metabolism, surface CO2 concentrations tend to be low while O2 concentrations are high.
How do the concentrations of CO2 and O2 vary with depth in the oceans?
Carbon dioxide concentrations increase with increasing depth, but oxygen concentrations usually decrease through the mid-depth and then rise again towards the bottom/
How is heat different than temperature?
-Heat is ENERGY produced by random vibrations of atoms or molecules, a measure of how many molecules are vibrating and how rapidly they are vibrating.
-Temperature is an object's response to the input of removal of heat, records only rapidly the molecules of a substance are vibrating. HOW HOT SOMETHING IS
What is heat capacity?
Heat capacity is a measure of the heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius.
What is latent heat?
Latent heat is the heat needed to change phases or state of a substance.
Ex: water to ice
What is residence time of an element in seawater?
It is the average length of time an element spends in the ocean.
How do you calculate residence time?
Using the equation:
(Amount of element in the ocean)/ (the rate at which element is added to or removed from the ocean)
How do temperature and salinity influence the solubility of gas in seawater?
Gases increase as temperature and salinity rises, and decrease as temperature rises and salinity falls
-as temp and salinity increase, the solubility decreases
Why does ice float?
The density of liquid water is higher than that of ice.
How is the ocean stratified by density?
The least dense water on top and the most dense water on the bottom.
What physical factors are involved in stratifying the ocean?
Because water has low viscosity, denser water masses sink to the bottom, whereas less dense water masses lie nearer the surface.
-Also, deep water masses have a rather narrow range of temperature & salinity while most variability in temp and salinity occurs in surface or near- surface waters.
What names are given to the ocean's density zones?
Surface Zone, Pycnocline, and deep zone
What are the thermocline, halocline and pycnocline?
depth ranges in the ocean.
Are thermocline, halocline and pycnocline related to temperature, salinity and density of seawater?
Pycnocline- density of seawater
Are thermocline, halocline and pycnocline the same in all places in the ocean?
No, there is typically no pycnocline in high latitudes because there's little difference in density.
What are the main factors that influence plankton blooms?
Abundance, nutrients, sunlight, the right temperature and cysts
What are the connections between large scale wind patterns and the pattern of surface ocean circulation?
Most of Earth's surface wind energy is concentrated in each hemisphere trade winds (easterlies & westerlies). waves on the sea surface transfer some of the energy from the moving air to the water by friction. The tug of wind on the ocean surface beings a mass flow of water. The water flowing beneath the wind forms a surface current.
What is a gyre?
- A gyre is a circuit of mid-lattitde current around the periphery of an ocean basin
-Continents and basin topography often block continuous flow and help deflect the moving water into a circular pattern.
-The rotation direction is clockwise in Northern hemisphere and counter clockwise in SH
What factors determine the large-scale pattern of surface ocean circulation in the N. Atlantic?
-The balance of wind, energy, friction, the Coriolis Effect and the pressure of gradient propels gyres and holds them along the outside of ocean basins.
-gulf stream, western boundary gyres, and wind
Are there any differences between the flow of surface waters on the Eastern and Western side of ocean basins. If so, what are they?
Yes, the pileup of water in the rotating gyre is NOT symmetric in the center of the gyre.One noteworthy aspect of gyre circulation is the tendency of western boundary currents to be intense. This results from the pile up of water along the western boundary of the ocean basin which forces the water to be focused along the western basin wall.
What are the similarities and differences between gyres and large scale ocean surface currents in the northern and southern hemispheres?
In the northern hemisphere, gyres move clockwise and in the southern hemisphere, they move counterclockwise. They both push the water eastward at the southwest in the northern hemisphere and the north west in the southern hemisphere
Large scale pattern of winds. What are the main cells?
The main cells are Hadley Cells (Northeasterly & Southeasterly Trades), Ferrel Cells (westerlies), and Polar cells
Why do the main cells produce a regular pattern of low and high pressure at specific latitudes?
Because of the Coriolis Effect - air turns to the right in the NH and to the left in the SH
-due to the wind associated with them
Why do the winds generally come from the east for locations from 30 degree S to 30 degree north?
When air has traveled from the equator to the pole (30 degree S and 20 degree N) the air becomes dense enough to fall back toward the surface. In the NH, the Coriolis deflects the surface air to the right and the air blows across the ocean/land from the Northeast
What is the general pattern of heating on earth, averaged over a year?
-more solar energy is absorbed in the tropics. Heat is then transferred to higher latitudes, until reaching the polar regions and then coming back down with cold air. The polar regions receive the warmer air masses - coldest regions. Absorbs heat again; then the cycle repeats.
Is it random or is there a systematic variation as a function of latitude?
There is a systematic variation as a function of a latitude.
What are the main factors that determine how heat is transported from low to high latitudes?
Heat is transported from the tropics to higher latitudes by ocean and atmosphere to partially compensate from uneven heating of the earth.
What is the Edman Spiral?
It explains that water at sea surface moves at an angle to the wind direction.
-The Ekman spiral predicts that the net motion of surface water is 90 degrees to the right of the wind direction in the N. Hemisphere and 90 degrees to the left of the wind direction in the south pacific.
model assumes that a homogeneous water column is being set in motion by wind blowing across its surface. The Coriolis effect causes the resulting surface current to move at 45 degrees to the right of the wind in the Northern Hemisphere
In response to the Westerly and NE Trade winds, Ekman transport pushes water toward 30 deg. latitude and this water "piles up" at this latitude
Think about the connections between surface currents and deep water in the ocean. What makes water sink from the surface and become deep water?
Density makes water sink from the surface and come deep water.
How does deep water circulation play a role in heat transfer and global ocean circulation?
As temp drops, the density of seawater increases until it exceeds the density of water below. At this point, the surface water sinks and begins to travel around the ocean basins where it is upwelled to the surface. This deep circulation is part of the mechanism for transferring heat from low to high latitudes.
Think about how temperature and salinity and density vary with depth in the ocean. What do these curves look like, on average, in the tropics vs. the mid-latitudes vs. polar regions.
-Tropics = low density, with moderately warm water and low salinity
-Mid-latitudes = density in the mid-range with relatively cool water and salinity
-polar regions = typically very dense, with extremely low temperatures and high salinities
Temperature decreases as the depth increases. Salinity increases as the depth increases. Density increases as depth increases. As the latitude increases, the change in temperature decreases from surface to deep parts.
What is the photic zone and why is it important?
It is the thin film of lighted water at the top of the surface zone. It is important because The photic zone is the layer where photosynthesis can still occur because the waves of light still penetrate the water. It is where all the production of food by photosynthetic marine organisms take place. Here, water is heated by the sun, transferred from the ocean in to the atmosphere and space, gases are exchanged with the atmosphere an most of the ocean's life is found here
Do all wavelengths of light penetrate seawater in the same way?
No, shorter (blue) wavelengths penetrate deeper than longer (red) wavelengths. The energy of some colors of light is converted into heat or absorbed nearer to the surface than energy of other light colors. Clear ocean water looks like blue because blue light can travel through water far enough to be scattered back through the surface to our eyes while the other colors are absorbed relatively quickly.
Why is photosynthesis important in the oceans?
Because it provides the basis for "food chains" in the marine realm and produces the organic matter which is the source of energy for nearly all other ocean life.
How does photosynthesis affect the concentration of dissolved gases in the oceans?
Photosynthesis plants and animals consume carbon dioxide and produce oxygen.
Why is mixing of deep waters up into surface waters important for life in the oceans?
Because the deep water contains rich in nutrients that marine organisms need for growth.
What role do bacteria play in the oceans?
The bacteria take the organic matter and convert it into nutrients which is then recycled into the surface water and reused as nutrients for the phytoplankton and fish.
If there were no bacteria in the oceans, what effect would that have on the amount of carbon that got buried in sediments at the bottom of the ocean?
Organic matter could not be broken down and there would be an abundance of carbon sediments.
What are the major groups of phytoplankton?
Diatoms, Coccolithophorids and dinoflagellates.
What are the main factors that influence seasonal variations in phytoplankton?
Seasonal changes of light (sun angle/ hours of daylight), seasonal changes in water - column stability (more stability, less nutrients mixed to the surface) and predator/prey interactions), and changes in "grazing" by zooplankton.
"changes in latitude, changes in attitude"
The Coriolis effect
explains that any freely moving object at or above the Earth's surface that moves horizontally through a long distance for a relatively long period of time will appear to veer to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.