1. Tides
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2. How do we describe tides?
Tides are the rise and fall of the sea around the edge of the land.
The greatest height to which the tide rises on any day is known as “high tide.”
The lowest height to which the tide drops on any day is known as “low tide.”
In mixed tides, there can be high-high tide, high-low tide, low-low tide, and low-high tide.

3. How do we describe tides?
Flood tide – as the tide is rising, we call it a flood tide
Ebb tide – as the tide is falling, we call it an ebb tide
Slack water – in between tides, when the tide is neither rising nor falling, we call it slack water

4. How are tides different around the world?
Tides behave differently in different place.
Diurnal tide – one high tide and one low tide each day
Semidiurnal tide – two high tides, two low tides each day of the about same height
Semidiurnal mixed tide – two high tides, two low tides of differing heights

5. When do tides occur? The tidal day is different from a regular day.
Unlike a regular day (24 hours), the tidal day lasts 24 hours and 50 minutes.
Therefore, high and low tides occur 50 minutes later each day.

6. What causes tides?
Tides are caused by the gravitational attraction between Earth, Moon, and Sun
Even though the Sun is larger, the Moon has a greater impact on tides than the Sun.
The phases of the moon affect the tidal range (difference in height between high and low waters).

7. Types of tides
When the Sun, moon, and Earth are in a straight line (full moon and new moon), the tides have the greatest range between high tides and low tides (extreme highs and extreme low).
This is called a SPRING TIDE.

8. Types of tides
When the Sun, moon, and Earth are at a 90 degree angle (first quarter moon and last quarter moon), the tides have the smallest range between high tides and low tides (below average high and above average low).
This is called a NEAP TIDE.

9. Tidal side effects
Tidal currents – currents associated with rising and falling tides in coastal water
Tidal bore – the wave front that moves into shallow water or up into a river ahead of an incoming tide.
Large tidal ranges - Some areas experience extreme tides on a daily basis, such as the Bay of Fundy in Canada.