There are two types of currents in the ocean: 1) surface currents move the water above the pycnocline a) ≈ 10% of the ocean b) horizontal motion c) wind powered = solar powered 2) thermohaline = deep currents move the water below the pycnoline (zone of rapid change of water density) a) ≈ 90% of the ocean b) horizontal and vertical motion c) density driven density depends temperature and salinity these are also solar powered 3) these two sets of current are interconnected Chapter 7 – Ocean Circulation Surface currents are moved by friction between the surface winds and the water surface = wind driven. max speed is 3% of wind speed Since winds are solar powered, surface currents are solar powered. The overall pattern of surface currents is controlled by the Coriolis effect, gravity, and the shape of the ocean basin. Like Fig 7.7, p. 205 Ekman Transport – the net (or average) motion of wind driven water, is 90° to the direction of the wind. In a perfect world, this movement is: 90° to the right in the Northern Hemisphere, 90° to the left in the Southern Hemisphere, WHY?...........the Coriolis Effect Fig. 9-, p. 236 In the northern hemisphere, the Westerlies tends to move water southeast, while the Trade winds move water northwest! wind direction wind-driven water movement (Ekman Transport) The Westerlies (30° - 60°) and the Trade Winds (0° – 30°) are the strongest winds,* and are the main winds causing ocean currents! Largest change in temperature causes the strongest wind! Remember, according to Ekman Transport, wind - driven water moves 90° to the wind direction. In the northern hemisphere, the Westerlies tends to move water southeast, while the Trade winds move water northwest! The movement of wind-driven water can be described with a vector = an arrow pointing in the direction of travel and scaled to the speed. This vector can be broken up into a component moving toward the edge of the ocean and a component moving toward the center of the ocean. wind direction water movement vectors of water movement The water moving east or west (toward the edge of the basin) bounces off of the land. In the northern hemisphere, the water current turns right! Current bounces off land Current bounces off land Subtropical Convergence = a short (≈ 6.5 feet tall) hill of water formed when part of the wind blow water moves to the center of the ocean basin. Can water stand in a hill? No! Gravity works to move the water back downhill. BUT the wind is still working to push water uphill again So – The winds build the hill taller, and The taller the hill the more gravity pulls the water back downhill The hill continues to grow until wind driven Coriolis deflected motion in = gravity driven motion out. Then – only the circular movement around the edge of the hill is left. THIS IS THE SURFACE CURRENT! Garrison, 2009, Essentials of Oceanography Under the hill of wa ...

1. There are two types of currents in the ocean:
1) surface currents move the water above the pycnocline
a) ≈ 10% of the ocean
b) horizontal motion
c) wind powered = solar powered
2) thermohaline = deep currents move the water below the
pycnoline (zone of rapid change of water density)
a) ≈ 90% of the ocean
b) horizontal and vertical motion
c) density driven
density depends temperature and salinity
these are also solar powered
3) these two sets of current are interconnected
Chapter 7 – Ocean Circulation
Surface currents are moved by friction between the surface
winds and the water surface = wind driven.
max speed is 3% of wind speed
Since winds are solar powered,
surface currents are solar powered.
The overall pattern of surface currents is controlled by the
Coriolis effect, gravity, and the shape of the ocean basin.
Like Fig 7.7, p. 205
Ekman Transport – the net (or average) motion of wind driven
water, is 90° to the direction of the wind. In a perfect world,
this movement is:

2. 90° to the right in the Northern Hemisphere,
90° to the left in the Southern Hemisphere,
WHY?...........the Coriolis Effect
Fig. 9-, p. 236
In the northern hemisphere, the Westerlies tends to move water
southeast, while the Trade winds move water northwest!
wind direction
wind-driven water movement (Ekman Transport)
The Westerlies (30° - 60°) and the Trade Winds (0° – 30°) are
the strongest winds,* and are the
main winds causing ocean currents!
Largest change in temperature causes the strongest wind!
Remember, according to Ekman Transport, wind - driven water
moves 90° to the wind direction.
In the northern hemisphere, the Westerlies tends to move water
southeast, while the Trade winds move water northwest!
The movement of wind-driven water can be described with a
vector = an arrow pointing in the direction of travel and scaled
to the speed.
This vector can be broken up into a component moving toward
the edge of the ocean and a component moving toward the
center of the ocean.
wind direction water movement
vectors of water movement

3. The water moving east or west (toward the edge of the basin)
bounces
off of the land.
In the northern hemisphere,
the water
current
turns right!
Current bounces off land
Current bounces off land
Subtropical Convergence = a short (≈ 6.5 feet tall) hill of water
formed when part of the wind blow water moves to the center of
the ocean basin.
Can water stand in a hill?
No!
Gravity works to move the water back downhill.
BUT the wind is still working to push water uphill again
So – The winds build the hill taller, and
The taller the hill the more gravity pulls the water back
downhill
The hill continues to grow until wind driven Coriolis deflected
motion in = gravity driven motion out.
Then – only the circular movement around the edge of the hill
is left.
THIS IS THE SURFACE CURRENT!

4. Garrison, 2009, Essentials of Oceanography
Under the hill of water, the pressure causes the thermocline to
sink deeper. So the hill at the surface has a root beneath it.
Sounds like isostasy doesn’t it?
The North Atlantic
Surface
Current
Gyre…
Surface currents flow around the edge of ocean basins…
Definitions
Gyre – a circular set of currents flowing around the edges of an
ocean basin.
There are 5 current gyres in the world today: Northern
Pacific, Southern Pacific, Northern Atlantic, Southern Atlantic,
Indian Ocean
The West Wind Drift or Antarctic Circumpolar Current ≠ a
gyre
It flows around a continent, not around an ocean basin
Geostrophic flow = Earth Turned = the type of current found in
a gyre. The movement of these currents is a balance between
wind, gravity, and Coriolis Effect, along with the presence of
land masses to block and bounce the currents.

5. Fig. 7.5, p. 203
The 5 great geostrophic current gyres!
N. Pacific gyre
S. Pacific gyre
N. Atlantic gyre
S. Atlantic gyre
Indian gyre
And the non-geostrophic (non-gyre) West Wind Drift
What would happen if the winds become consistently stronger?
Move water would be moving
The hill would grow bigger
Gravity –driven water motion increases to balance the
increased wind-driven movement
Stronger currents would result
What would happen if the winds stopped?
The currents would lose energy and die away.
Fig. 7.8, p.207
The hill in the center of each gyre is offset to the west. Why?
Because the water in the ocean sloshes west as the Earth rotates
to the east.
As long as there is no change in wind speed, there is no
movement of water into or out of the center of the gyre.
This area becomes an ecological desert -> no nutrients = no life
The Sargasso Sea in the N. Atlantic is an example.
http://www.bermuda-triangle.org/html/sargasso_sea.html

6. Even though each gyre is one continuous flow of water, we
divide them into 4 separate types of currents. Each behaves a
little differently!
Current typeNorth Atlantic Ex.North Pacific Ex.
SpeedVolumeTemperatureDepthMid-latitude
TransverseNorth Atlantic CurrentNorth Pacific
Currentmoderate20 – 30 SVcoolingmoderateEastern Boundary
(EBC)Canary CurrentCalifornia Current10’s km /day10 – 15
SVcoldshallow
(500 m)Tropical TransverseNorth Equatorial CurrentNorth
Equatorial Currentmoderate30 SVwarmingmoderateWestern
Boundary
(WBC)Gulf StreamKuroshio Current
100’s km/day50 – 100 SVwarmdeep (2 km)
SV = sverdrups = 1,000,000 m3/sec = 32,000,000 ft3/sec
Western Intensification = the difference between Western
Boundary Currents and Eastern Boundary Currents
Western Boundary Currents (WBC) are warmer, faster,
deeper, and move more water. They also have sharp
boundaries.
Eastern Boundary Currents (EBC) are colder, slower,
shallower, and move less water. They have diffuse boundaries.
But WHY??????????

7. 1) The trade winds converge at the equator and blow extra water
to the west.
2) The water in the ocean sloshes west as the Earth rotates to
the east – sea level is about 6 feet higher in the west than in the
east.
3) The hill of water is offset to the west, which pinches the
western boundary current narrower and makes it move faster.
But how can we constantly move more water…
1) there are smaller sub-currents that move water from
pole to the equator parallel to the EBC
Garrison, 2012, Essentials of Oceanography
2) Eddies or “whirlpools” which spin off from the sharply
defined edges of the WBC.
a) these gradually move eastward across the ocean basin
b) they extend to the seafloor and create “storms” on the
seafloor as they pass
c) eddies last for up to 3 years.
d) make up about ¼ of the North Atlantic Ocean
3) Countercurrents and undercurrents at the equator carries
water from west to east.
There are other, smaller current gyres in the world’s oceans =
the subpolar gyre. These are influenced by the polar easterly

8. and westerly winds, so spin the opposite way than their
subtropical cousins
There are other, non-geostrophic surface currents in the world’s
oceans. These form when geostrophic currents such as the Gulf
Stream encounter land masses and split apart. The path of
these currents is controlled by the configuration of land instead
of the Coriolis Effect
From Garrison, Invitation to Marine Science (2010)
Remember, the oceans exert tremendous influence on weather
and climate.
This map shows summertime patterns of winds on the west and
east coast of North America. Warm ocean currents are shown in
red; cold currents, in blue. Air is chilled as it approaches the
west coast and warmed as it approaches the east coast.
The weather can influence the currents, too. Here, the seasonal
monssons alter the pattern of the surface currents in the Indian
Ocean.
Winds shift seasonally. Why?
Land warms and cools faster than the ocean does
Shifting winds reverse the direction of surface current
flow.

9. Some Definitions
Downwelling = downward movement of surface water toward
the seafloor
Upwelling = upward movement of deep or bottom water
brings cold, nutrient rich water to the sunlit surface
usually accompanied by high productivity (lots of life)
increased nutrient supply provides “food” for plants
increased plants provides food for plant eaters,
and up the food chain…
LOOKS LIKE CONVECTION AGAIN!
http://www.redmap.org.au/resources/impact-of-climate-change-
on-the-marine-environment/upwelling-and-downwelling/
El Niño = The Southern Oscillation = a periodic shift in the
atmospheric pressure zones in the tropical Pacific Ocean
a) this causes reversals of wind direction, current flow,
and weather patterns IN THE PACIFIC ONLY.
b) happens every 3 to 8 years
(getting more frequent?)
c) predictable about 1 year in advance
1982-3 and 1997-8
were the two worst El Niño events In recent history
Fig.
Pattern of high and low atmospheric pressure during a “normal”
or non - El Niño year.
Figure 7.22, p. 221

10. In a “normal” year,
1) high pressure in the eastern Pacific (near us)
2) low pressure in the western Pacific (near Japan)
3) trade winds blow from east (high pressure) to west (low
pressure)
4) currents move warm water to pool up in the western
Pacific
5) upwelling of nutrient rich water along the eastern
Pacific (west coast of the Americas)
a) anchovy fishery near Peru
6) cool temperatures, low rainfall in the eastern Pacific
7) warm temperatures, high rainfall in the western Pacific
(the monsoons)
Pattern of high and low atmospheric pressure during an El Niño
year.
Figure 7.22, p. 221
In an “El Niño” year,
1) low pressure in the eastern Pacific (near us)
2) high pressure in the western Pacific (near Japan)
3) trade winds reverse
4) currents reverse
5) upwelling shuts down along the eastern Pacific and the
anchovy fishery in Peru crashes
6) warmer than normal temperatures, above average
rainfall in the eastern Pacific
a) flooding and landslides common

11. 7) cooler temperatures, lower than average rainfall in the
western Pacific
a) drought and wildfires common
8) shift in temperatures cause mobile species to migrate,
attached species to have reduced populations or die out.
Figure 7.22, p. 221
La Niña = an overcompensation when the ocean tries to return
to a “normal” or non- El Niño pattern. This happens because
the ocean sloshes!
The eastern Pacific experiences colder than normal water
temperatures, causing cold, usually
dry weather conditions there.
The western Pacific has
extra warm water and warmer
and more rainy weather.
These (usually) happen
only after extra strong El Niño events.
Thermohaline Circulation
Density driven
Vertical and horizontal water movement
Moves ≈ 90% of the ocean’s water at any time
Rates of movement are very slow
Surface Currents move about 1.5 m/sec
Deep Currents move about 0.01 cm/sec (< 1/1000th as fast)
Carry water, heat, and nutrients throughout the deep ocean
basins
Can take as much as 1,600 years + to make the trip!

12. How and why does the water move vertically in the ocean?
Upwelling and downwelling is how…
Where does this happen?
Many places, for many reasons…
Coastal Ekman Transport causing upwelling. Are we north or
south of the equator here?
Coastal Ekman Transport causing downwelling
Like figure 7.12 p. 211 in text
http://www.atmos.washington.edu/2004Q4/211/Lecture10_notes
.html
Wind Driven upwelling. This only happens near the equator
where the Coriolis effect is minimal.
Wind Driven downwelling. This only happens near the equator
where the Coriolis effect is minimal.
http://www.frf.usace.army.mil/eopTemp/eopTempWind.shtml
Equatorial upwelling occurs where the trade winds blow water
away from the equator, leaving a hole that is filled by upwelling
of relatively shallow water.
Also see fig. 7.10 p. 210
Top View
Side View
Current convergence = where a surface current impacts land or
where two or more surface currents collide (these cause
caballing and downwelling)

13. Current divergence = where a surface current pulls away from
land or where two surface currents pull away from each other
(these cause upwelling)
Current Convergence
Current Divergence
Remember water masses??????
Water Mass = a body or layer of water with similar temperature
and salinity (so density) characteristics.
These form at the surface due to the conditions found there,
then sink…
Just what the heck is Caballing?
Not in textbook!
When two surface currents meet, they combine to form a water
mass that is denser than either of them.
This new water mass sinks or downwells to its equilibrium
depth (all water below it is more dense and all water above it is
less dense).
This vertical motion is part of the ocean’s deep or thermohaline
circulation.
While all this caballing is happening at surface current
convergences…
Deep water upwells again where surface currents diverge!
As the currents pull apart, they leave a “hole”
The lower pressure pulls water up from deeper in the ocean to
fill the hole

14. nutrients come too…
Sounds kind of like convection again, doesn’t it??????
TypeUpwellingDownwellingCoastal Ekman Transport (not at
equator since there is no Coriolis there)Wind // to shore such
that Ekman transport moves water toward the oceanWind // to
shore such that Ekman transport moves water toward
landCoastal Wind Driven (near tropics)Wind blows toward the
shoreWind blows away from the shoreEquatorial (at equator
only)Trade winds blow water away from
equatorNoneThermohalineSurface current divergenceSurface
current convergence (caballing)
Surface water
Central water
Intermediate water
Deep water
Bottom water
Most of the world’s ocean has 5 distinct layers, all of which
formed at the surface and downwelled to their equilibirum
depth.
Surface water 0 – 200 m
Central water 200 – base of thermocline
Intermediate water – base of thermocline –
1500 m
Deep water 1500 m – 4000 m
Bottom water 4000 M +
Where does the ocean not have 5 distinct layers?
The poles where it is cold and salty top to bottom

15. This makes vertical movement easy here
This figure shows the general flow of water in the ocean
Deep currents (thermohaline) and surface currents connect in
areas of convergence (downwelling) and divergence
(upwelling).
Fig. 7.29, p. 228
The Arctic current convergence - where the Greenland and
Labrador currents meet and sea ice forms – creates very cold,
very salty, and so very dense water which sinks to the deep sea
floor to form the North Atlantic Deep Water.
NADW flows south along the deep sea floor
Near Antarctica, very cold, very salty water forms at the
Antarctic Ice Shelf. This sinks to form Antarctic Bottom Water
– the densest water mass in the ocean. This sinks to the deep
seafloor and flows northward, forcing the North Atlantic Deep
water to the surface at the Antarctic Divergence. It upwells or
returns to the surface along the west coasts of landmasses and in
the northern Pacific Ocean.
Notice that the deepest water in the Atlantic Ocean forms at
high latitudes. WHY?
Surface water is the coldest and saltiest = the densest.

16. Once these water masses form, they sink and travel slowly
along the seafloor.
North Atlantic Deep Water (NADW) forms at surface current
convergences near 60° N, sinks and flows south
Antarctic Bottom Water (AABW) forms near the Antarctic Ice
Shelf and sinks to flow north.
Is NADW or AABW more dense?
The thermohaline circulation "conveyor belt“ transfers heat
throughout the oceans. Purple arrows indicate cold, deep ocean
currents. Red arrows show shallow, warm water circulation
patterns. Credit: Image courtesy CLIVAR (after W. Broecker,
modified by E. Maier-Reimer)
Breaking News / Climate Change in Action
2005 data shows that the total volume of the northern part of the
Gulf Stream has decreased by 1957.
The Gulf Stream is a western boundary current and carries
massive quantities of heat toward the north pole
Data also shows The Atlantic Ocean is becoming less salty as
the Earth warms, there is more rain, and the ice caps melt
It appears that the lower salinity (less dense) surface water does
not sink as fast or as deep
Less downwelling means less “pull” of Gulf water north to fill
the “hole” as the water sinks.
As the Gulf Stream slows, it brings less warm water to Europe,
and winters there may become more extreme (cold and stormy)

17. Chapter 6
Air – Sea Interactions
Weather = present state of the atmosphere
Climate = long term average weather in a particular area
The FIRST picture sent back from the International Space
Station http://www.technochitlins.com/archives/space/
Heat in = heat out when averaged for the whole world (ignoring
global warming)
Earth has maintained an average temperature of 16° C for
many thousands of years.
BUT…
There are significant departures from this balanced heat budget
model!
http://connect.in.com/snowman/images.html
http://image-go.net/palm-tree-pictures.html
Departures from the balanced heat budget:
1) variation in solar heating with latitude. You know it is
warmer in the tropics and colder near the poles. Here’s why –
the angle the sun’s rays hit the Earth:
a) The sun’s rays hit the surface at 90 ° in the tropics,
1) concentrates the energy
2) less reflection of light back to space
3) less time in atmosphere = less absorption and back
scattering

18. b) lower angle of incidence near the poles,
1) spreads the solar energy over a larger area
2) more light reflected back into space
3) more time in the atmosphere = more backscattering
/ absorption
4) snow and ice at the poles reflects the sun back to
space
Fig. 6.3, page 167
Winds and ocean currents move heat from the tropics (too much
solar heating) to the poles (too little solar heating.
Departures from the balanced heat budget:
1) variation in solar heating with latitude – the angle the
sun’s rays hit the Earth.
2) the seasons.
Here’s why – the 23.5 ° tilt of the Earth on its axis of
rotation.
Fig. 6.2, page 164
Fall (Autumnal) Equinoxes = the first day of fall
equal day and night everywhere
the sun is opposite the equator.
Winter solstice = the first day of winter.
North has the shortest days and the longest nights.
South has longest days and shortest nights (and summer).
The sun is opposite 23.5 ° S.
North of the Arctic Circle at 66.5 ° N, there is 24 hour

19. darkness,
South of the Antarctic Circle at 66.5 ° S, there is 24 hour
light.
Spring (Vernal) Equinox = the first day of spring
equal day and night everywhere
the sun is opposite the equator.
Summer solstice = the first day of summer
North has the longest days and the shortest nights.
South has the longest nights and the shortest days (and
winter).
The sun is opposite 23.5 ° N.
North of the Arctic Circle at 66.5 ° N, there is 24 hour
light,
South of the Antarctic Circle at 66.5 ° S, there is 24 hour
darkness.
Departures from the balanced heat budget:
1) variation in solar heating with latitude.
2) the seasons.
3) the land responds to seasonal variations more drastically
than the ocean does.
a) the ocean has thermal inertia – it resists changes in
temperature.
b) the land responds to solar heating about 4 times
faster than water does
Average yearly difference in temperature by latitude.
Note change in scale for land (right margin) and ocean (left
margin)

20. Departures from the balanced heat budget:
1) variation in solar heating with latitude.
2) the seasons.
3) The thermal response of land vs. sea.
3) Day and night variations in solar heating.
http://www.andrewkelsall.com/spectacular/category/photos/page
/2/
Composition of the lower atmosphere – a nearly homogeneous
mixture of:
Nitrogen (N2) = 78%
Oxygen (O2) = 21 %
Argon (Ar) = 0.9%
Carbon Dioxide (CO2) = 0.04%
Air also contains water vapor (humidity) in amounts that vary
from place to place and day to day (depends on temperature and
pressure). It can make up as much as 4% of the total volume.
Fig. 6.5, p 168
Does air have mass?
Yes! Since air is matter, it has mass (it weighs something).
A 1 cm x 1 cm column extending from the surface to the top of
the atmosphere weighs over 2 pounds.
A 1 ft x 1 ft column extending through the atmosphere weighs
over a ton!
SO… If there is a ton of pressure pushing down on us all the
time, why aren’t we all as flat as pancakes?

21. Because – we have a ton of pressure pushing back out again.
Since pressure in = pressure out, we don’t feel a thing!
This is the same mechanism used by organisms living at the
bottom of the ocean.
So, for all organisms, living under pressure is not the issue, it is
change in pressure that can make us sick (or kill us)!
Just as with water, the density of air can change. What factors
will affect the density of air?
1) Temperature – as T density will
-as T density will
2) Humidity – as Humidity density will
as Humidity density will (dry air is more
dense)
a) AND warm air can hold more water vapor than cold air,
so it becomes even less dense!
3) Pressure – as Pressure density will
(falling air = compressing air = warming air)
as Pressure density will
(rising air = expanding air = cooling air)
Low Pressure
High Pressure
Remember this important rule:
As air rises, it cools and expands => it can’t hold as much water
vapor.
Where air is rising (low pressure), the climate tends to be rainy!
http://www.cksinfo.com/nature/weather/rain/index.html

22. As air falls, it warms and compresses => it can hold more water.
Where air is falling (high pressure), the climate tends to be
warm and dry!
http://www.edupic.net/Images/Biomes/desert_saquaro167.JPG
Air moves / winds form because of
differences in density from place to place!
Fig. 6.7, p. 169
Low Pressure
High Pressure
High Pressure
Low Pressure
Fig. 6.8, p. 169
Convection in the atmosphere due to differences in air pressure!
http://www.ux1.eiu.edu/~cfjps/1400/circulation.html
Our first model – Convection on a non-rotating, water-covered
Earth, assuming no loss of heat to space.
Air rises at the equator and sinks at the poles. Horizontal winds
exist to connect these areas of vertical air motion.
What happens at the equator where warm, humid air rises?
RAIN!!!
Effect of the Earth’s rotation = The Coriolis Effect
Different latitudes at the Earth’s surface are at different

23. distances from the Earth’s axis of rotation
Each latitude has to spin at a different speed to make one
rotation per day.
This causes an apparent deflection of the direction of movement
of an object moving free of friction with the Earth’s surface.
But the Earth does rotate, and it does have land, and seasons,
and…
How does this change our model?
The Coriolis Effect causes objects moving without friction with
the Earth’s surface to apparently deflect from their straight-line
path.
Objects north of the equator will always deflect to the
right
Objects south of the equator will always deflect to the left
The Coriolis Effect is 0 near the equator and increases the
closer to the poles you get.
Another factor we ignored in our perfect world model of the
Earth’s winds was the constant loss of heat from the upper
atmosphere into space.
What happens to air as it gets colder?
Cold air gets more dense and it sinks!
Now let’s see what happens when we include the Coriolis Effect
and heat loss in our wind model (we are still ignoring seasons
and the effect of land for now).

24. Fig. 6.12, p. 174
Vertical air motion (up or down) occurs at:
The equator (0 °) where warm, humid air rises. The
Doldrums.
As the air rises, it cools and expands, causing the
water vapor to condense and fall as rain. Think Hawaii…
Vertical air motion (up or down) occurs at:
30 ° N and 30 ° S, where cold, dry air sinks. The Horse
Latitudes.
The air warms and compresses as it sinks, allowing it
to absorb water vapor, There is little rainfall here. Think the
Sahara Desert…
Vertical air motion (up or down) occurs at:
60 ° N and 60 ° S, where warmish, humid air rises.
As the air rises, it cools and expands, causing the
water vapor to condense and fall as rain. Think Seattle….
Vertical air motion (up or down) occurs at:
90 ° N and 90 ° S, where extremely cold, dry air sinks.
Again, there is little precipitation here. The polar
regions are technically deserts based on their average
precipitation.
Winds are named for the direction they blow from!
Looking at the Northern Hemisphere, horizontal air motion
occurs between:
0 ° and 30 °N (the Hadley Cell). Surface winds here want
to blow toward the equator but are deflected to the right by
Coriolis. In the Northern Hemisphere they blow from NE to SW
and are called the NE Trade Winds.
30° N and 60° N (the Ferrel Cell). Surface winds here

25. want to blow toward the pole but are deflected to the right by
the Coriolis Effect. In the Northern Hemisphere they blow from
SW to NE and are called the Westerlies.
60° N and 90 ° N Surface winds here want to blow from
the pole toward the equator but are deflected to the right by
Coriolis. In the Northern Hemisphere they blow from NE to SW
and are called the Polar Easterlies.
In the Southern Hemisphere, the wind pattern is a mirror image
of the winds in the Northern Hemisphere. WHY?
Because Coriolis deflects things to the left here!
We’ve ignored a few things with our 3-convection cell per
hemisphere model!
1) Local variation in wind patterns due to diurnal (day / night)
variations.
In the day,
the land warms > than the sea. Warm air rises over
land
cool air sinks over the ocean, onshore wind develops.
At night,
the land cools > than the sea. Cool air sinks over land
warm air rises over the ocean, offshore wind pattern
develops.
We’ve still ignored a few things with our 3-convection cell per
hemisphere model!
2) The seasons change the pattern of solar heating and
length of day vs. night

26. Latitude Shortest day Longest day
012:0712:071011:3212:422010:5613:203010:1414:04409:2014:0
0508:0516:21605:5418:49700:0024:00800:0024:00900:0024:00
July = summer in the north.
ITZC (inter-tropical convergence zone ≈ meteorlogical equator)
moves slightly north of the equator.
January = summer in the south. ITZC moves slightly south of
the equator.
Sea level pressure climatology, averaged over 1958 – 1997,
from NCEP-NCAR reanalysis projects. Units are millibars.
High pressure occurs where relatively cold air sinks, low
pressure happens where relatively warm air rises. Take away:
the ocean is colder than land in summer, warmer than land in
the winter.
3) We also need to worry about the effect of land, which warms
up and cools down faster than the ocean does.
In the Northern Hemisphere, winds swirl clockwise around high
pressure (sinking) air, and counterclockwise around low
pressure (rising) air.
3) We also need to worry about the effect of land, cont.

27. January sea-level atmospheric pressure and the resulting wind
patterns, figure 6.13, p. 177.
Regional variation in wind patterns due to the influence of the
seasons combined with the presence of land vs. sea:
Summer-time pattern
L
H
Non-rotating world wind
Real world wind
L
H
Regional variation in wind patterns due to the influence of the
seasons:
Winter-time pattern
H
H

28. Definitions
Storms = regional atmospheric disturbances, characterized by
strong winds and, usually, precipitation.
These can be very powerful:
11/70 Hurricane in Bangladesh – winds to 120 mph,
storm surge 40’ high (in a country only 8’ tall on average),
killed > 300,00 people
8/2005 Hurricane Katrina – winds to 125 mph, rain up
to 10 inches per hour. Loss of life and damage were
exacerbated by poor design and maintenance of the levee
system.
Storms are cyclonic – huge, rotating masses of low pressure air.
There are two main types of storms.
extratropical cyclones (form outside of the tropics)
tropical cyclones (form in the tropics)
Air mass = a large body of air with nearly uniform temperature
and humidity so density.
For example, the polar air mass (cold and dry)
Tropic air mass (warm and humid)
Front = a boundary along which 2 air masses interact or collide.
example: the polar front between polar and temperature
air masses
Along a front, the air masses don’t mix. Instead the denser air
slides under and
lifts the less dense air upward.
There are two kinds of fronts – cold fronts and warm fronts.
Figure 6.16, p. 181

29. Cold fronts form when the cold air runs into warm air.
Warm fronts form when the warm air runs into cold air.
Occluded fronts form where a warm front, a cold front, and a
very cold front collide.
Extratropical Cyclones – Our Storms
An extra-tropical cyclone primarily gets its energy from the
horizontal temperature contrasts that exist in the atmosphere.
Extra-tropical cyclones (also known as mid-latitude storms) are
low pressure systems with associated cold fronts, warm fronts,
and occluded fronts.
L
Stage 4
Extratropical cyclones form over small bends in the front
caused by local low pressure zones.
1) They gain their energy from the temperature differences
across the developing fronts.
2) ET cyclones begin to lose energy and die away once an
occluded front forms and/or once the storm travels over land
3) They last between 2-5 days after they form.

30. 4) Most of “ours” form in the Gulf of Alaska and are blown by
the jet stream over the west coast and then across the continent.
http://www.weatherquestions.com/What_is_a_cyclone.htm
Tropical cyclones (in the tropics), in contrast, typically have
little to no temperature differences across the storm at the
surface and their winds are derived from the release of energy
due to cloud/rain formation from the warm moist air of the
tropics
http://earthobservatory.nasa.gov/IOTD/view.php?id=43154
Tropical Cyclones
(Small) tropical storms<tropical depressions<hurricanes
(Large)
huriccanes = typhoons = cyclones = williwilli (depending
on where you are)
hurricanes are swirling masses of air up to 9 miles tall
central low pressure “eye” of rising air up to 10 miles wide
surrounded by bands of rain clouds hundreds of miles
across
travel at east and north at speeds of 5 – 35 mph
a single hurricane contains more energy than the US uses
in 20 years.
The formation of Tropical Cyclones is not well understood:
They form within a single air mass between 10 – 25 ° N
and S
Originate with a bend in the winds over a local low
pressure (usually over warm land)
Grow once over warm water (why?)

31. Rising humid air cools, condenses and releases latent
heat to power the winds.
Once started, it takes 2-3 days for a tropical storm to grow
to a hurricane
Worldwide, we average 100+ hurricanes (cyclones/typhoons)
per year.
Conditions needed to grow a hurricane:
Warm water (the warmer the stronger the storm)
Warm, moist air to supply the latent heat
The Coriolis Effect to cause the winds to twist!
No hurricanes will start at the equator. Why?
No Coriolis Effect there
Few hurricanes in the South Atlantic due to high wind shear and
few “starter” storms
Tropical Cyclone Tracks for the last 150 years.
How Hurricanes Kill:
1) strong winds up to 200 mph
2) rain fall of up to 1” per hour or more
3) storm surge = a bulge of water pulled up by a
combination of the low atmospheric pressure vacuuming the
water upward and the strong winds pushing the water onshore
(usually the most deadly)

32. Hurricanes are measured in 5 categories on the Saffir Simpson
Scale
Chapter 7 – Ocean Circulation
Read: The entire chapter
Vocabulary:
Surface Currents vs. Deep Currents
Dynamic Topography
Gyres
Subtropical Gyres - be sure you know the location and flow
direction
Equatorial Currents
Western Boundary Currents (WBC)
Northern / Southern Boundary Currents
Eastern Boundary Currents (EBC)
Subpolar Gyres
Ekman Transport
Subtropical Convergence
Geostrophic Current
Western Intensification – why and how balanced
Currents and Climate
Coasts next to WBC vs. coasts next to EBC
Asian Monsoons
Upwelling & high surface productivity vs. downwelling
Surface current divergence and upwelling
Surface current convergence and downwelling
Coastal upwelling and downwelling
Offshore wind and upwelling / Onshore wind and
downwelling
Important surface currents
Antarctic Circumpolar Current
The Gulf Stream

33. Eddies
Normal Pacific conditions and Walker Circulation
Warm Pool
Peruvian Fisheries
El Niňo / Southern Oscillation
Effects (changes from normal circulation)
Timing
La Niňa
Effects (changes from normal and El Niňo conditions)
Prediciting El Niňo
Thermohaline Circulation
T / S diagrams
Important bottom currents (where formed and how they
flow)
Antarctic Bottom Water (AABW)
North Atlantic Deep Water (NADW)
Antarctic Intermediate Water (AAIW)
Oceanic Common Water
Role of Oceanic Conveyor Belt in moving heat, nutrients, and
oxygen
Homework:
1) Compare and contrast surface and deep (thermohaline)
currents. Answer S if the statement applies only to surface
currents, D if the statement applies only to deep currents, or B
if the statement applies to both types of currents.
a. The sun is the ultimate source of energy causing water to
move ___
b. Move approximately 10% of the water in the ocean ___
c. Move about 90% of the water in the ocean ___
d. Move water both horizontally and vertically ___
e. Move water only horizontally ___
f. Water speeds approach those of rivers on land ___
g. Water speeds much, much slower than rivers on land ___
h. Created by downwelling due to density changes at the
surface.

34. 2) Which of the following contribute to geostrophic or surface
current flow? Circle all that apply. a) friction b) the presence
of land c) temperature d) gravity e) Coriolis Effect f) density
3) How many subtropical geostrophic current gyres exist in
today’s oceans? Where are they located?
4) The Antarctic Circumpolar Current is a surface current gyre.
T or F?
5) Fill in the chart below describing the 4 legs of a geostrophic
current gyre:
Current Leg
Water Temperature – use warm, cooling, cold, or warming
Water Speed – use slow or fast
Water Volume -
range in Sverdrups
Example
Mid-latitude Transverse Current
Eastern Boundary Current

35. Equatorial Transverse Current
Western Boundary Current
6) What is Western Intensification? Why does it occur?
7) Which of the following help balance Western Intensification?
Circle all that apply! a) countercurrents and undercurrents at the
equator b) eddies c) both
8) Compare and contrast upselling and downwelling. Answer U
if the statement relates to upwelling, D if the statement relates
to downwelling.
a. Causes water to sink to deeper depths in the ocean ___
b. Causes water to rise to the surface from deeper depths ___
c. Associated with high productivity (lots of life) ___
d. Created by surface current convergence ___
e. Occurs when winds move parallel to the shore such that
Coriolis Effect moves water away from land ___

36. f. Occurs in the tropics when wind blows directly onshore ___
g. Created by surface current divergence ___
9) The situation shown in the map at right will result in
upwelling. Note: this area is in the southern hemisphere. T or F?
wikipedia.org
10) Deep and bottom currents form at high latitudes because
there is no pycnocline here to block downwelling. T or F?
11) Concept check 7.4 #3 Describe changes in atmospheric and
oceanographic phenomena that occur during El Niňo / La Niňa
events, including changes in atmospheric pressure, winds,
weather, equatorial surface currents, coastal
upwelling/downwelling and the abundance of marine life, and
sea surface temperature.

37. Chapter6: Air – Sea Interactions
Read the entire chapter.
Vocabulary:
Variations in Solar Heating
Seasons
Tilt of Earth’s axis of rotation
Vernal Equinox
Tropic of Cancer
Summer Solstice
Autumnal Equinox
Tropic of Capricorn
Winter Solstice
Special circumstances north of the Arctic Circle and south of
the Antarctic Circle
Effects of latitude
Diurnal (dat ot night)
Response of land vs. sea – from lecture
Properties of the atmsophere

38. Chemical makeup
Temperature
Greenhouse Effect
Controls on Density of the atmosphere
Effect of temperature
Effect of humidity
Effect of Pressure
Moving Air
Effect of difference in air pressure
Wind
Winds on a non-rotating, water covered world
Coriolis Effect
Variation with latitude
Direction in Northern vs. Southern Hemisphere
Effect on Wind
Global Wind Patterns
Circulation cells = convection cells
Pressure zones

39. Equatorial low pressure (the Doldrums)
Intertropical Convergence Zone = the ITCZ
Subtropical high pressure (the Horse Latitudes)
Subpolar low pressure (Polar Front)
Polar high pressure
Wind Bands (where are they located and in what direction do
they blow)
The Trade Winds
The Westerlies
The Polar Easterlies
Weather vs. climate
Air mass
Front
Cold front
Warm front
Storm
Tropical Cyclone

40. Hurricane = cyclone = typhoon
Generation and power source
Saffir – Simpson Scale (what it is, not specific #)
Structure of a tropical cyclone
Eye
General patterns of movement
Destruction
Storm Surge
Extra Tropical Cyclone = from lecture
Where and how formed
Movement path
Ocean Climate: precipitation (rainor snow), seasonal variation
in temperature, etc
Equatorial
Tropical
Subtropical
Temperate
Subpolar
Polar

41. Energy from the sun – wind power
Homework: Name _________________
1) Briefly explain how the following phenomena result in
uneven heating of the Earth’s surface:
a) Latitude (distance from the equator) –
b) Tilt of the Earth’s axis of rotation –
c) Variation in the response to solar heating of water vs. land –
d) Day vs. night –

42. 2) Winter occurs in the same months in both the southern and
northern hemisphere. T or F?
3) If there is a net annual heat shortage (out > in) at the poles,
and a net annual heat gain (in > out) at the
equator, why doesn’t the heat difference between the poles and
equator increase over time?
a) Heat stored in water vapor at low latitudes is moved by winds
to high latitudes.
b) Heat stored in warm ocean water at low latitudes is moved by
ocean currents to high latitudes.
c) Both of these apply.
4) Which of the following are true about the Coriolis Effect?
Circle all that are true. Hint: not all are true!
a) The Coriolis Effect results from rotation of the Earth about
its axis.
b) The Coriolis Effect causes a true deflection or bending of the
path of objects moving free of friction
with the Earth’s surface (you can see the bending from space).
c) The Coriolis Effect causes the path of moving objects to bend
to the right in both the northern and
southern hemisphere.

43. d) The Coriolis Effect is zero at the equator and increases
toward the north or south pole.
5) Answer the following questions about the atmosphere:
a) What is the composition of the atmosphere-
b) What does the term humidity mean? How can we have 80%
humidity?
c) What happens to the temperature of air in the troposphere
(lowest layer in the atmosphere) with
distance above sea level?
d) List the three factors that control the density of air, and
explain how the density varies as each
changes (increases / decreases).

44. 6) Warm air can hold more water vapor than cold air. T or F?
7) Water vapor (steam) is denser than air. In other words, water
vapor sinks in air. T or F?
8) Rising air can hold more water vapor than air at the Earth’s
surface. T or F?
9) On the diagram of the Earth next page, indicate the following
things:
a) Zones of high pressure (H) and low pressure (L) at the
Earth’s surface.
b) The location and direction of any vertical air motion in the
lower atmosphere
c) The location and direction of the following surface winds:
The NE and SE Trade Winds, the
Westerlies, the Polar Easterlies.
d) Areas of high annual rainfall, and the desert belts.

46. 0°
30° N
60° N
30° S
60° S
90° S
90° N
10) Match the following terms with the descriptions below.
a. Air mass
b. Front
c. Polar front
d. Cyclone
e. Storm

47. f. Latent Heat of Evaporation / condensation
___ Swirling mass of low pressure air in which winds converge
and rise
___ Layer of air with constant temperature, pressure, and
humidity so density
___ Zone at which polar air (the polar easterlies) and
temperature air (the westerlies) meet
___ Regional atmospheric disturbance characterized by strong
winds and often, precipitation
___ Boundary between air masses of different density.
___ Heat needed to evaporate water, or released when water
vapor condenses.
11) The terms below refer to storms. After each term, place an
E if it applies to extra tropical cyclones, T if it
applies to tropical cyclones, and B if it applies to both.
Cyclonic storm ___
Form at a front between two air masses ___
Form within a single air mass ___
Storm most common in California ___
Grow in size and strength over warm water (> 25° C) ___

48. Winds are turned by the Coriolis Effect ___
Obtain energy from latent heat released as water vapor
condenses ___
Lose energy and die away over land ___
Obtain most of its energy from temperature differences ___
Form near the equator ___