GEL 16 Study Guide - Final Guide: Secchi Disk, Intertropical Convergence Zone, Redfield Ratio
Lecture 6: Seawater chemistry and the Carbon Cycle
- Sublimation: Occurs due to vapor pressure
- Salinity: Total quantity of dissolved inorganic solids in water.
- Why are hydrogen bonds important in water? Hydrogen bonds are important for life
o How many hydrogen bonds per water molecule?
- Why is sublimation different than latent heat? Sublimation occurs due to vapor pressure
and latent heat = fusion (highest of all common liquids) vaporization (highest of all
common substances)
- What is the photic zone, and what is the typical depth vs maximum depth? The photic
zone is the thin layer of water at the surface that is lit by sunlight. Can be up to 600m in
the tropics, but typically is top 100m
- What wavelength of visible light penetrates deepest into the water? Blue light is
transmitted farther than other wavelengths of light (to ~300 m)
- What is a Secchi disk and how is it used? It is used to measure the clarity of water. Use
a Secchi Disk for the depth of clarity. You lower the disk into the water, keep lowering it
until it can no longer be seen, record that level, then raise and record the level when you
see the disk again.
- What is the temperature of maximum density for fresh water and average salinity
ocean water?
- What is the freezing point of seawater? Freezing point of seawater = -1.7 degrees C
- What does it mean for salinity to be called conservative in seawater? Conservative
unit of seawater occurs in constant proportions, even if levels changes. Note: non-
conservative unites change with seasonal, biological or short geological cycles i.e. use by
things like algae. How does this differ for things like nutrients?
- What is the Redfield ratio? (note, all 4 components discussed in class) The Redfield
ratio is the ideal ratio of nutrients required for photosynthesis C:N:P:Si, 106:16:1:15
o Is this ratio conservative?
- Describe some natural processes that increase or decrease salinity in the ocean:
rivers (major way we add salt to the ocean) rivers and groundwater – volcanic activity,
hydrothermal vents, organisms shells… sea spray
o Where is salinity highest in the ocean? Which ocean is the saltier: Atlantic or
Pacific? Why?
o Describe salinity sources and sinks.
- What is E vs P and how does this affect salinity? Dry areas of Earth E>P → high
salinity – Wet areas of Earth E<P →low salinity…evaporation, precipitation
- Is the ocean becoming progressively saltier? No, the ocean is in chemical equilibrium.
The proportion and amounts of dissolved solids remain constant. This concept is known
as the “steady state ocean”
- How do salinity and temperature affect the density of seawater?
- What gas has the largest volumetric concentration in the ocean? CO2 is the gas with
the greatest volumetric concentration in the ocean
- What is the P:R ratio?
o How does this relate to the abundance of oxygen vs CO2 in the oceans?
- When CO2 enters the ocean, what are the 3 chemical forms that it dissociates into?
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o Which of these forms is most important (i.e. most easily utilized) for biology in
the ocean?
- What is the average pH of the oceans? Seawater is slightly alkaline, with a Ph of about
8.0
- What controls the pH of the oceans? CO2 controls the Ph/the acididty. CO2 controls
the Ph of the ocean.
- Of the existing reservoirs of carbon (CO2) on Earth, which is the largest?
Lecture 7: Atmosphere properties
- Troposphere: The lower part of the atmosphere is called the troposphere
- Stratosphere: The upper part of the atmosphere is called the stratosphere
- Weather: is the day to day changes in atmospheric circulation patterns
- Climate: Is the averaging of weather over many years
- Coriolis effect: The Coriolis effect is the observed deflection of a moving object, caused
by the moving frame of reference on the spinning Earth.
- Jet stream: The region of high-altitude winds called jet streams play a role in wind
systems and storm tracks.
- ITCZ: Intertropical convergence zone, this forms the boundary between the N and S
Hadley Cells
- Which layer of the atmosphere contains weather and also is where planes typically
fly? The troposphere contains weather and is also where planes typically fly
- What gas type has degraded the ozone in the southern hemisphere over time? There
is an Ozone hole over Antarctica caused by release of chlorofluorocarbons (=CFC or
Freon)
- Does CO2 affect the Ozone layer? The ozone is NOT made or destroyed by CO2, the
greenhouse effect is totally separate from the ozone removal effects
- Greenhouse gases absorb and re-radiate energy in what band? IR band radiation, i.e.
long wave
- How does this lead to the greenhouse effect?
- Describe how Ozone is naturally produced and destroyed in the atmosphere.
- How much of the heat on Earth is redistributed by the atmosphere vs the oceans?
- Which direction are winds deflected in the Northern or Southern hemispheres due
to the Coriolis effect? In the Northern Hemisphere air turns to the right, in the Southern
Hemisphere air turns to the left
- Explain how atmospheric pressure affects air flow and storm patterns.
- What are the names of the 3 atmospheric circulation cells? Hadley cells (tropical cells
found on each side of the equator), Ferrel cells (found mid-latitudes), Polar cells (found
near the poles)
- Identify the location of these cells on a diagram.
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- What are the differences between the Trade winds and the Westerlies? Trade winds
are surface winds of Hadley cells, the westerlies are surface winds of Ferrel cells.
- What are the differences between the doldrums and the horse latitudes? Doldrums
are calm equatorial areas where two Hadley cells converge, the horse latitudes are areas
between Hadley and Ferrel cells (little surface wind in this area)
- How does E vs P affect atmospheric circulation? Sub-tropical Hi pressure; E>P yields Hi
Salinity, Equatorial and Polar latitudes; E<P yields Low salinity
Lecture 8: Winds and Ocean Circulation
Sea Breeze: summer monsoon warm moist air moves on to land – lots of rain
Land Breeze: winter monsoon cool dry air flows away from land – little rain
Monsoon: Monsoons are patterns of wind circulation that change with the season. Areas with
monsoons generally have dry winters and wet summers.
Gyre: The Coriolis effect modifies the course of ocean currents. The end result is a circular
pattern called a Gyre.
Upwelling: Upwelling is the directed movement of water away from a source, with replacement
of that volume from deeper water sources drawing oceanic waters towards the surface.
Upwelling is very important for bringing nutrients to the surface for productivity
Thermohaline circulation: Temperature/salt influenced= density) deep ocean circulation driven
by temperature and salinity
Teleconnections: To the rest of the globe, indirect effects that are observable and measurable,
but not a result of insitu changes
-Be able to describe the American Monsoon, including when it occurs and what
geographical regions of America are affected by the precipitation. North America has a
“classic” style (summer) monsoon
Covers Western Mexico, AZ, NM
Note: this is NOT typical CA winter precipitation
Winter Monsoon - NE/SE Trades dominate; dry air flows off Himalayas
Summer Monsoon - Asia gets moist air and rain because of flow from the ocean
-Where does the majority of the moisture come from for the NA Monsoon? AZ, NM, some
Western Mexico
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Document Summary
Lecture 6: seawater chemistry and the carbon cycle. Salinity: total quantity of dissolved inorganic solids in water. Sublimation occurs due to vapor pressure and latent heat = fusion (highest of all common liquids) vaporization (highest of all common substances) The photic zone is the thin layer of water at the surface that is lit by sunlight. Can be up to 600m in the tropics, but typically is top 100m. Blue light is transmitted farther than other wavelengths of light (to ~300 m) It is used to measure the clarity of water. Use a secchi disk for the depth of clarity. You lower the disk into the water, keep lowering it until it can no longer be seen, record that level, then raise and record the level when you see the disk again. Freezing point of seawater = -1. 7 degrees c. Conservative unit of seawater occurs in constant proportions, even if levels changes.
