Understanding Tides And Their Computations: Maryland Tide Finder

Factors Contributing to Tides

A small shorebird called the red knot, which winters in Argentina near the tip of South America, and summers in the arctic, times its migration so that it arrives in the Delaware Bay area just after the horseshoe crab eggs have been laid.  It feeds on the newly laid horseshoe crab eggs to provide the sustenance it needs to complete its fight of over 12,000 miles.  This stop may be one of just two or three during the entire flight.

1.  Can you think of any other cycles in nature that are monthly or tied to the Moon?

To the average person, the comings and goings of the tide might seem random and patternless.  Most of us however are aware that there are things called “tide tables” that are printed in local newspapers that tell when we can expect high and low tides to occur at our location, wherever that may be.  What causes the tides, and just how can they be predicted?  The answer will be the focus of this project.

    To being this Project the students will need to get a tide table.  Go to the Maryland Department of Natural Resources website 

http://www.dnr.state.md.us/fisheries/access/tide_finder.html

For simplicity go to the “Maryland Ocean Side” and select “Ocean City (Fishing Pier).”   At the bottom of the page select September for the month, start on September 1, and ask for 14 days of information, the maximum.  Then hit “Get Info.”  The result should be a table that for each day has high tides, low tides, the height of the tide above or below average (- values), sunrise and sunset times, moonrise and moonset times, and “% Moon Visible.”  The last quantity essentially tells the phase of the Moon:  100% visible means the Moon is full, 50% visible means the Moon is at quarter phase, 0% visible means the Moon is new.  Print this table.  

The student will need to collect a months worth of data by changing the start date from 1 to 15 to 30 and repeating the process 3 times.  

The next part of this Project will involve analyzing this data.  For this we will use the spreadsheet MoonTides.xls.  Notice that in the printed tide table, most days have two high and two low tides.  What we want to do is find the Average High Tide for each day and the Average Low Tide for each day, and place this data in the spreadsheet in the indicated column for each (if a day only has one high or low tide, just use that number, and be careful to add and subtract negative numbers properly).  Next compute the difference between the Average High and the Average Low Tide for each day and place this in the spreadsheet.  Also fill in the % Visible of the Moon for each day.  

2.  Now that we have the data in the spreadsheet, determine which days (should be 2) have the greatest difference (Column 4 in the spreadsheet) between Average High and Average Low tides?  What is the % Visible of the Moon for the corresponding days?  Which days (again should be 2) have the least difference (again Column 4) between Average High and Average Low tides?  What is t he % Visible for the Moon on these days?  

3.  What is the phase of the Moon for the four occasions?  Using your knowledge of lunar phases, draw a diagram for each of the days illustrating the positions of the Earth, Moon and Sun.  Use the diagram and your knowledge of gravity to explain why there are these differences at these particular times.  

High tides that are higher than normal are known as spring tides.  They occur about every 2 weeks year round and correspond with low tides that are lower than usual. They have nothing to do with the spring season, but are named from a German word that means “to rise up.”  

High tides that are lower than normal and low tides that are higher than normal are called neap tides. They likewise occur about every two weeks year round.  

4.  Tides are also affected by a number of factors other than the phase of the Moon, including weather and geography.  Storm winds can push water into (or out of) particular areas and create tides of even greater magnitude than normal.  This was what occurred during Hurricane Isabelle locally and during Hurricane Katrina in New Orleans, though lesser storms will also have an effect.  Look at a map of the Chesapeake Bay and determine what effect southwest winds would have on the normal tide pattern? How about northwest winds?

First and foremost, tides are denoted as a generic term. It is the elementary concept mainly used in defining the falling as well as the rising in the overall sea level and the analysis main essentially taken in line with the land. The rising and the falling recording primarily result from the existing gravitational attraction between the sun and the moon. Conversely, there are small instances in which the tides tend to occur in the makeable large lakes, within the parametric solid crust as well as in the atmosphere.  The occurrence of the tides at any moment mainly facilitated with the gravitational forces sun and the moon. This paper thus, focuses on the tides recorded in the Maryland Tide Finder and the overall computations regarding the low, high and the percentage of the visible moon (Fuller, Luan, & Quataert, 2016).

1. What causes the tides, and just how can they be predicted?

The primary factor and the key contributors to the emerging tides are the sun as well as the gravitational pull.  Furthermore, the rising and the falling in the tides also instigated and accelerated through the actions of the centrifugal forces often generated via the rotation of the earth. Moreover, it is important to note that the overall impacts of the tides mainly grounded on the relationships existing between the moon, the earth and the sun at any designated moment. Notably, the moon is depicted to have the greatest influence on the parametric tides since it close to the earth in comparison to the sun. Subsequently, the rotation of the moon result around the makeable earth impacts on the seas by causing it to bulge. The effects often happen to be immense in the situations in which the gravitational pulls tend to be greater. On the other hand, the rotation of the moon on the opposite direction also causes the centrifugal forces induced on the earth surface to result in second portion of bulging across the globe. Furthermore, the high tides mainly manifested along the low waters.  Conversely, the high tides often predicted and manifested twice in every 24hours as well as depicted for at most 50 minutes (Bertone et al. 2016, February).

The high tends gives the reflection on the overall time which the moon tend to last in rotating the earth. Furthermore, the denoted extra 54 minutes gives the reflection on the average alteration times which occur from one day to the other.  Notably, the lunar tides often modified by the existing solar tides and they are accelerated by the forces of gravity in line with the sun.

The data gathered and applied in computing the overall tides and the moon mainly summarized as indicated in the figure below  

Results Mainly Indicated as follows

Graph Showing the analysis (Daher et al., 2016, December).  

2. Now that we have the data in the spreadsheet, determine which days (should be 2) have the greatest difference (Column 4 in the spreadsheet) between Average High and Average Low ti!des? What is the % Visible of the Moon for the corresponding days?

Date 13^th and corresponding percentage of visible moon- 2

 Which days (again should be 2) have the least difference (again Column 4) between Average High and Average Low tides?  What is the % Visible for the Moon on these days?   Date 2rd and the corresponding percentage of visible moon 78

3. What is the phase of the Moon for the four occasions?  Using your knowledge of lunar phases, draw a diagram for each of the days illustrating the positions of the Earth, Moon and Sun.  Use the diagram and your knowledge of gravity to explain why there are these differences at these particular times.  

The four phases of the moon mainly illustrated in line with the lunar month and  this is designated at 29.53days. This is the duration which the moon takes to move to the overall next phase. Lunar month makes the overall phases of the moon.

References

Bertone, S., Arnold, D., Jaeggi, A., & Hosseini, A. (2016, February). Bernese Developments in Planetary Geodesy: our Latest Solution of Moon Gravity Field and Tides and an Outlook on Future Projects. In AGU Fall Meeting Abstracts.

Daher, H., Arbic, B. K., Ansong, J. K., Adcroft, A., Cornuelle, B. D., Lau, H. C. P., ... & Müller, M. (2016, December). Tidal energy dissipation over long geological timescales. In AGU Fall Meeting Abstracts.

Fuller, J., Luan, J., & Quataert, E. (2016). Resonance locking as the source of rapid tidal migration in the Jupiter and Saturn moon systems. Monthly Notices of the Royal Astronomical Society, 458(4), 3867-3879.

Roberts Jr, W. H. (2015). Homeowner Association Resident’s Perceptions on Stormwater Retention Ponds and Clean Drinking Water:(Montgomery West Homeowners Association (MWHOA) Gaithersburg, Maryland).