Water, Water,
Everywhere
TIDES, CURRENTS, & WAVES

Welcome to the ocean planet.

326,000,000,000,000,000,000 gallons.

Average depth of the ocean is 13,124 feet.

The deepest point in the ocean is
The Mariana Trench
near the Phillipines.
This trench has a maximum depth of
36,200 feet.

SEAWATER (1kg)
35 g
fresh water
other
components
965 g

DISSOLVED GASES
% %
in in
ATM ocean
nitrogen 78% 48%
oxygen 21% 36%
carbon dioxide .04% 15%

TIDES =>
• LUNAR TIDES
-gravitational force
between earth & moon
• “bulge” forms on
side facing moon

TIDES =>
• “bulge” forms on
opposite side
due to inertia
• How many tides/day?

TIDES =>
• “lunar day” is
24 hr. & 50 min.
• orbital plane of moon
is inclined 28.5º

TIDES =>
• SOLAR TIDES are
caused by the SUN
and are 1/2 the height
of lunar tides

TIDES =>
• “constructive”
interference leads to
“SPRING” tides
• “destructive”
interference leads to
“NEAP” tides

TIDES etc. =>
• TIDAL RANGE is the
difference between high
to low water
• TIDAL CURRENTS are due
to flow of water in or out of
a bay or harbor

TIDES etc. =>
 FLOOD CURRENT is
water flowing in due
to rising tide
 EBB CURRENT is
the outflow due to
falling tide

TIDES etc. =>
• SLACK WATER is the
still water between
tide changes
• tidal currents can
reach 3mi/hr

OCEAN CURRENTS
• A combination of 4 things
circulates the ocean in the
Atlantic, forming “gyres”.

4 forces of current:
• surface winds
• the sun’s heat
• the Coriolis effect
• gravity

The NORTH ATLANTIC
gyre
• a series of four
interconnecting currents:

• The Gulf Stream
• The North Atlantic Current
• The Canary Current
• The North Equatorial Current

STUDYING CURRENTS
• FLOAT METHOD
• depends on movement of a free-floating
object
• FLOW METHOD
• measure current as it flows past a fixed
point

sometimes big big boats sail the
ocean blue…

sometimes
it gets purrrty
windy…

and other
times…

ACCIDENTAL
DATA?
• May, 1990:
• The Hansa Carrier
• 21 boxcar-sized cargo
containers lost
• containing 30,910 pairs of
Nike shoes!

ACCIDENTAL
DATA?
• pairs were not tied
together
• beachcombers placed ads,
held swap meets, etc…
• oceanographers noticed
ads

ACCIDENTAL
DATA?
• requested where and
when information on shoe
findings
• refined computer models
of the North Pacific gyre
• some completed a FULL
circuit of the gyre!

ACCIDENTAL
DATA?
• January 1992, freighter
lost 29,000 rubber ducks,
etc. in the N. Pacific
• recovered from 500mi of
Alaskan shoreline

WAVE
CLASSIFICATION
• by the DISTURBING FORCE:
• wind
• storm surges
• landslides
• seismic activity
• volcanic eruptions

WAVELENGTH
A B
crest
height
trough

orbital path of
individual water
molecule at water
surface

FREQUENCY:
number of wave crests passing
point A or point B each second
A B

PERIOD:
time required for wave crest
at point A to reach point B
A B

TYPICAL
WAVELENGTHS
• WIND WAVE:
60-150m (200-500ft.)
• SEISMIC SEA WAVE
(tsunami):
200km (125mi.)
• TIDE:
1/2 circumference of Earth

TROPICAL STORM
FORMATION

FORMATION
• area of storms moving
off African coast…
“cape verde” storms
• converging winds cause
storm to begin rotation
• requires WARM water to
continue dev. (80ºF)

FORMATION
• water vapor rises quickly
• often continues until it
hits land in the W. hemisphere
• sometimes moves over colder
water or is sheared off by
easterly winds

IF DEVELOPMENT
CONTINUES
• A TROPICAL DISTURBANCE is an
organized area of storms for at
least 24 hrs.
• A TROPICAL DEPRESSION is an
area of low pressure with defined
circulation

IF DEVELOPMENT
CONTINUES
• A TROPICAL STORM is a strong
area of low press. and max.
sustained winds 39-73mph.

IF DEVELOPMENT
CONTINUES
• A HURRICANE has maximum
sustained winds over 73 mph.
• usually 200-250 miles in
diameter

• EXAMPLES
of hurricanes:

• Sept. 2004 – Hurricane
Frances approaches Florida…

• Sept. 2004 – Ivan in Texas,
Jeanne nearing Bahamas

• Sept. 2004 – Hurricane Jeanne
nearing Bahamas with 115mph. winds

• Sept. 2004 – Hurricane Jeanne
makes landfall at Port St. Lucie…

stay in touch…
http://www.nhc.noaa.gov/

Can it be the end??