1. Tides

2. Tides
Tides are the rhythmic rise and fall of the ocean’s water at a fixed location
Tides are extremely large waves
High tide is the crest of the wave
Low tide is the trough of the wave
Tides have a profound effect on marine organisms. Changing water levels creates hardships for coastal organisms, alternately exposing them to desiccation (drying out) and inundation (submerging in water)

3. Causes of Tides
Gravitational attraction of the Moon (Lunar Tide) and to a lesser degree the Sun (Solar Tide)
There would still be a tide even without the moon, it would be smaller and the difference between high tide and low tide would be less. The Sun is 27 million times larger than the Moon, but 400 times farther from the Earth
Centrifugal force – created by the Earth rotating on its axis

4. Tidal Differences
The Earth spins once every 24 hours, but the moon travels around the Earth as we spin. It takes a particular point on the Earth 52 min extra each day to “catch up” to the moon.
Tidal Period is 24 hrs 52 min

5. Differences in Tides are caused by
Size, shape and depth of the oceans basins
Season (more to do with solar tides)
Time of the month (effects mostly lunar tides)
Coriolis effect
Amphidromic points – a point that does not rise and fall with the tides (the water rotates around it)

6. Tidal Range
The tidal range is the vertical distance between the high tide and low tide
Example: if the high tide is 6.3 m and low tide is 1.2 m would make the range 5.1 m
The tidal range is at its greatest during the SPRING tide. This corresponds with the full moon and the new moon phases (not the season). This occurs twice every lunar month (29.5 days) when the Moon, Earth, and Sun are aligned.

7. The attractive forces of the sun and moon pull water in the same direction and we observe higher high tides and lower low tides than normal
Full Moon
New Moon

8. Tidal range is at its least during the NEAP tide, which occurs during the first and third quarter phases of the moon (twice every lunar month). This is when the Moon and Sun are at a 90° angle with respect to the Earth.
The attractive forces of the sun and moon pull water in different directions and we observe a lower high tide and a higher low tide than normal.
Third-quarter
First-quarter

9. Types of Tides
Diurnal Tide – only 1 high tide and one low tide each day
Example: Northern parts of the Gulf of Mexico and Vietnam
Semidiurnal Tide – 2 high tides (of fairly equal height) and 2 low tides (of fairly equal height)
East coast of United States
Mixed Tides – 2 high tides (of different heights) and 2 low tides (of different heights)
West coast of United States