ocean tides
DESCRIPTION
Ocean Tides. By Coach Murray. Lesson Objectives. Define the term tide Explain examples of tidal range Describe how an observer sees tides in real life List reasons why tides are important Explain the two major causes/types of tides Describe how tides are predicted. Ocean Tides. - PowerPoint PPT PresentationTRANSCRIPT
Ocean TidesBy Coach Murray
Lesson ObjectivesDefine the term tideExplain examples of tidal rangeDescribe how an observer sees tides in real
lifeList reasons why tides are importantExplain the two major causes/types of tidesDescribe how tides are predicted
Ocean TidesWhat is a tide:
Is the periodic rise and fall of the sea surfaceNoticeable against coastlines, not in the open
oceanIs just a long period wave
How do I observe tides?3 ways to observe tides:1. High – maximum elevation of a tide2. Low – fall in sea level to a minimum
elevation3. Slack – brief period of time in which water is
neither rising or fallingNotation:
0 is sea level, -0.5 is ½ ft. or 6” below sea level
What is tidal range?Tidal range – vertical difference between
high and low tidesExample
Nova Scotia0 to 35 ft range
Why are tides important?General NavigationCommercial harvestingHurricane damage prediction
Why are tides important?
Why are tides important?
The 2 major causes/types of tidesNewton’s law says…gravitational attraction
between the earth and 1) The moon (aka lunar tides) - Britanica video
The major cause, closer to Earth
2) The sun (aka solar)The minor cause, further from Earth
How does the lunar tide work?Hypothetically, if earth was covered completely
with water, two “bulges” of water would appear.1 bulge on side of earth facing the moon1 bulge on the opposite side of the globe
As earth makes 1 complete rotation (in 24 hrs) a single point would experience 4 events1) high, low, high, low
How does the solar tide work? Solar tide
IS NOT a separate set of tides GIVES variation to the lunar tidal pattern It is not referred to as the solar tide but the two effects is
has on the lunar tide: Spring tides
Sun, moon, and earth are aligned (@ new and full moon – 2 x a month) Result: extra-high high tides and very-low low tides
Neap tidesSun and moon at right angles to each other (2 x a month)Result: partial cancelation of lunar tide = moderate tides
How does the solar tide work? Solar tide
IS NOT a separate set of tides GIVES variation to the lunar tidal pattern It is not referred to as the solar tide but the two effects is
has on the lunar tide: Spring tides
Sun, moon, and earth are aligned (@ new and full moon – 2 x a month) Result: extra-high high tides and very-low low tides
Neap tidesSun and moon at right angles to each other (2 x a month)Result: partial cancelation of lunar tide = moderate tides
How does the solar tide work? The solar causes both spring and neap tides
to happen to the lunar tide.
Realistic Tides are PatternedRealistically our planet is not covered by
waterContinental landmasses
Block westward passage of tidal bulges as earth rotates
Result: tidal patterns vary daily from ocean basin or in different regions of ocean basins 2 highs, 2 lows (semidiurnal tide) 1 high, 1 low (diurnal or daily tide) 2 highs, 2 lows but successive high tides are quite
different from each other (mixed semidiurnal)
Tide PredictionsTides for coastal ports and locations (Fort
Morgan, Dauphin Island ) are have been observed and recorded for years
Future predictions of timing and amplitude are based on historical observations.
Published years in advance in books, calendars, and online by location.
Tide Measuring Devices