MOTION IN THE OCEAN
Motion in the Ocean: currents, waves and tides all move and
mix ocean waters
1.
Currents http://www.youtube.com/watch?v=e8nOowxO5-k
a. Coriolis Effect – deflection of winds and water due to
the rotation of the Earth
i. Toward the right in the northern hemisphere
(clockwise)
ii. Towards the left in the southern hemisphere
(counterclockwise)
http://www.youtube.com/watch?v=BPNLZyBNPTE
b. Gyres – large circular system of surface currents
produced by global wind patterns and the Coriolis
Effect
http://www.youtube.com/watch?v=x0EqbdSMC8E
c. Upwelling – currents and wind push away water from
the surface of the ocean, bringing cold, deep water up
from the bottom. Rising water is rich in nutrients
which attracts marine organisms to the area.
http://www.youtube.com/watch?v=XV90dy0ns1U
http://www.youtube.com/watch?v=APMzM-xYlOs
d. El Niño – a warming of the surface currents around
Christmas time in the eastern Pacific which stops
upwelling.
http://www.youtube.com/watch?v=B0D7NY6enIk
http://www.youtube.com/watch?v=7FVZrw7bk1w
e. Biological Effects of Currents
i. Allows for migration of marine organisms
ii. Food distribution
iii. Oxygenation of ocean water
iv. Distribution of heat
2. Waves – the undulation of currents that forms a
disturbance that moves along the surface of the ocean
http://www.youtube.com/watch?v=bQrj0DNXjMY
a. Crest – Top of the wave
b. Trough – Bottom part of the wave
c. White Cap – Strong wind pushes on the top of the
wave
http://farm1.staticflickr.com/168/443753222_036fb4014c_z.jpg?zz=1
d. Wave Height – Calculated by measuring the vertical
distance between the crest and the trough
e. Wave Length – Distance between two consecutive
crests or troughs
http://hrsbstaff.ednet.ns.ca/leal/Wave_Diagram.jpg
f. Breaker – Wave that loses it’s shape when it
approaches shallow water
http://www.youtube.com/watch?v=8y1MkFZSwIs&feature=endscreen&NR=1
g. Fetch – The span of water over which wind blows
generating the specific size of a wave
http://www.vos.noaa.gov/MWL/apr_06/Images/Wave-Fig-2.jpg
h. Swells – A wave with a flatter, rounder crest and
trough found in deeper waters
http://www.youtube.com/watch?v=qS0lJaxkFAE
i. Tsunami – (Seismic wave) The long, fast waves
produced by earthquakes or other seismic
disturbances of the sea floor
http://www.youtube.com/watch?v=P-T00d-0MGQ
http://www.youtube.com/watch?v=w3AdFjklR50
3. Tides – rhythmic rising and lowering of water caused by
the gravitational attraction of the sun and the moon
i. High Tide – water is deep
ii. Low Tide – water is shallow
http://www.youtube.com/watch?v=Rn_ycVcyxlY
 There is a six hour average between high and low tides
A. Three Types of Tides:
a. Diurnal – 1 high tide and 1 low tide per day.
i. Occurs in the Gulf of Mexico
b. Semi-Diurnal – 2 high tides and 2 low tides per
day; the tides are relatively equal in height, easy to
predict
i. Occurs on the east coast
c. Mixed – 2 high tides and 2 low tides per day;
height of tides not equal, difficult to predict
i. Occurs on the west coast
B. Tidal Currents – horizontal water movements caused by
tides; water periodically flows in one direction for awhile
and then reverses its flow in the opposite direction
a. Flood Current – Tide on the way “in”
b. Ebb Current – Tide on the way “out”
c. Slack Water – The period of no current in between
flood and ebb currents
d. Tidal Range – Vertical distance between high and
low tides
http://www.youtube.com/watch?v=qfhNjpu_IU4
http://www.youtube.com/watch?v=EnDJ6_XpGfo
e. Spring Tide – Greatest tidal range
f. Neap Tide – Least tidal range
g. Rip Tide – Caused by 2 converging currents or ebb
tides moving over an irregular surface
h. Biological Effects of Tides
i. Planktonic distribution
ii. Feeding and reproductive cycles
iii. Food
iv. Oxygenation