The Tidal Cycle

1
The Tidal Cycle

• What forces cause the rising and falling of the
  ocean tides?
• How often does the tide change?
• What environmental factors influence the height
  of the tides?
• What do the tidal flats look like at high tide?
• What do the tidal flats look like at low tide?

2
What Causes the Tides? Gravitational Pull from
the Moon and Tidal Inertia Results in Tidal Wave
that Rotates Around the Earth
3
Changes in the angle of the Moon result in
changes in the heights of high and low tides
4
MOON
LUNAR DAY 24 Hrs 50 min Result 2 high
tides every 12 hrs 25 min 2 low tides every 12
hrs 25 min
5
TIDAL VARIABILITY Lunar Tides gt Solar
Tides Spring Tides Alignment of Moon Sun /
High Amplitude Exchange Neap Tides Misalignment
of Moon Sun / Low Amplitude Exchange
6
Low Tide _at_ the Overlook 1.6 ft.
below MLLW
7
High Tide _at_ the Overlook 7.0 ft.
above MLLW
8
Low Tide _at_ Sloughside Pilings 1.6 ft.
below MLLW
9
High Tide _at_ Sloughside Pilings 7.0
ft. above MLLW
10
Low Tide _at_ Sloughside point 1.6 ft.
below MLLW
11
High Tide _at_ Sloughside Point 7.0 ft.
above MLLW
12
Low Tide _at_ the Overlook 1.6 ft. below
MLLW
13
High Tide _at_ the Overlook 7.0 ft.
above MLLW
14
Low Tide _at_ the Observation Deck 1.6 ft.
below MLLW
15
High Tide _at_ the Observation Deck 7.0
ft. above MLLW
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Locations and tide information for photos

• Low Tide (lower low) on June 7, 2004 predicted
  -1.6 _at_ 1035am at Coos Bay mouth using
  OSU/Hatfield Marine Science Center Dock, Yaquina
  Bay, OR
• High Tide (lower high) on June 7, 2004 predicted
  7.0 _at_ 535pm at Coos Bay mouth using OSU/Hatfield
  Marine Science Center Dock, Yaquina Bay, OR
• Photos taken June 7, 2004 at South Slough
  National Estuarine Research Reserve, Charleston,
  OR along the shoreline mid-estuary accessed from
  the Estuary Study Trail System. Low tide photos
  taken between 1045am 1115am (photographer -
  Tom Gaskill)
• High tide photos taken between 545pm 615pm
  (photographers - Tom Gabriel Gaskill)

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Real-time, Predicted, and Historic Tides are
Available On-line TidesOnline www.tidesonline.n
os.noaa.gov