The regular rising and falling of the sea level on a daily basis TIDES The regular rising and falling of the sea level on a daily basis

TIDE STAGES Tide Range High Tide Low Tide 1. High Tide (PG. 113): When the crest hits the shore: Sea level rises 2. Low Tide (PG 113): When the trough hits the shore, Sea level lowers 3. Tide range (PG. 113): Distance between high tide and low tide High Tide Low Tide Tide Range

TIDE STAGES CONT’D 4. Ebb Tide(PG 113): Outgoing Tide, Between High and Low 5. Flood Tide (PG113): Incoming Tide, Between High and Low

What causes tides?

TIDE FORMATION ACTING FORCES 1. Gravitation pull of the sun and moon 2. Centrifugal force of the earth’s rotation 3. Positions of the moon and the sun 4. Angle of the moons orbit

GRAVITATIONAL FORCES LUNAR MONTH = Tidal Month, 29.5 days, The tide is 50 minutes later each day NEW MOON + FULL MOON: The earth, moon and sun line up in a straight line= Spring Tides-These are extra high and extra low tides

Proxigean Spring Tide A very rare, unusually high tide. Occurs when the moon is both unusually close to the Earth and in the New Moon phase (when the Moon is between the Sun and the Earth). The proxigean spring tide occurs at most once every 1.5. years.

GRAVITATIONAL FORCES CONT’D FIRST QUARTER + THIRD QUARTER = Planets are at right angles, = Neap Tides: The gravitational pull on the earth is not as great so it results in medium size tides

ANGLE OF THE MOON’S ORBIT The moon has a tilted elliptical (oval shaped) orbit The distance the moon is from the equator is called the moon’s declination PERIGEE-Time when the moon is closest to the earth (Stronger pull on Earth) APOGEE-Time when the moon is furthest from the earth (weaker pull on Earth) Perigee Apogee

3 TIDE PATTERNS SEMIDIURNAL Tides: 2 high tides per day that have the same height-12 HOURS, 25 minutes apart, and 2 low tides per day that are the same height

2. Mixed Tides MIXED: 2 high tides and 2 low tides, but they are not equal heights

3. Diurnal Tides DIURNAL: 1 high tide every 24 hours and 50 minutes, EX. Gulf of Mexico

SPECIAL TIDE TIDAL BORE: Incoming high tide that enters a river and makes a wave (common during hurricanes and large storms)