Tides and Tidal PowerTides and Tidal Power

TidesTidesTides: Tides:

The periodic rise The periodic rise and fall of the sea and fall of the sea surface.surface.

Tide TermsTide TermsTidal Day: Tidal Day:

24 Hours, 50 minutes 24 Hours, 50 minutes (2 (2 high, 2 low each day)high, 2 low each day)

Tidal Period: Tidal Period: Time between successive Time between successive high (or low) tideshigh (or low) tides..

Tidal Range: Tidal Range: Difference Difference between the highest and between the highest and lowest tide levels.lowest tide levels.

Daily Inequality: Daily Inequality: Difference between the Difference between the heights of successive heights of successive high or low tides.high or low tides.

Note : Note : Tides change from week to Tides change from week to week.week.

Spring and Neap tidesSpring and Neap tidesSpring Tides:Spring Tides:These are peak high tides and minimum low tides These are peak high tides and minimum low tides

occurring at the new and full moon when the occurring at the new and full moon when the moon and sun are positioned in opposition to moon and sun are positioned in opposition to each other. each other.

http://www.sfgate.com/getoutside/1996/jun/tides.htmlhttp://www.sfgate.com/getoutside/1996/jun/tides.html

Neap Tides:Neap Tides:These tides are neither very high nor very low (the These tides are neither very high nor very low (the

tidal range is small) and occur when the sun and tidal range is small) and occur when the sun and moon are pulling against each other at the first moon are pulling against each other at the first and final quarters of the moon and final quarters of the moon

Cause of TidesCause of TidesAnimation:Animation:

http://www.pbs.org/wgbh/nova/venice/tides.htmlhttp://www.pbs.org/wgbh/nova/venice/tides.html

Tide TablesTide Tables

DFO Tide Tables:DFO Tide Tables:http://www.tides.gc.ca/english/Canada.shtmlhttp://www.tides.gc.ca/english/Canada.shtml

Tidal PowerTidal Power

A huge dam (called a "barrage") is built A huge dam (called a "barrage") is built across a river estuary. When the tide goes across a river estuary. When the tide goes in and out, the water flows through tunnels in and out, the water flows through tunnels in the dam. in the dam.

The ebb and flow of the tides can be used to The ebb and flow of the tides can be used to turn a turbine, or it can be used to push air turn a turbine, or it can be used to push air through a pipe, which then turns a turbine. through a pipe, which then turns a turbine.

If needed, large lock gates, like the ones If needed, large lock gates, like the ones used on canals, allow ships to pass.used on canals, allow ships to pass.

Annapolis Royal Tidal Power