Lesson 10A: TIDES

Lesson 10A: TIDES

Estimated Time: Two 45-minute class periods

Indicators(s): Core Learning Goal 1

1.4.1. The student will organize data appropriately using techniques such as tables, graphs, and

webs (for graphs: axes labeled with appropriate quantities, appropriate units on axes, axes

labeled with appropriate intervals, independent and dependent variables on correct axes,

appropriate title).

1.4.2. The student will analyze data to make predictions, decisions, or draw conclusions.

1.4.6. The student will describe trends revealed by data.

1.5.4. The student will create and/or interpret graphics (scale drawings, photographs, digital

images, etc.).

Indicators(s): Core Learning Goal 2

2.2.2. The student will explain the role of natural forces on Earth. At least: retention of an

atmosphere, an agent of erosion and deposition, tides and deep ocean currents

2.5.1. The student will investigate various physical cycles found in the natural world. At

least: rock cycle, water cycle, tides, lunar phases, eclipses, seasons

Student Outcome(s):

The student will be able to evaluate tidal patterns by analyzing tide tables.
The student will be able to explain why the tidal range changes during a month by analyzing data.
The student will be able to explain the causes of seasons by reading a technical selection and interpret it appropriately.

Brief Description:

During this lesson the student will generate tidal curves from tide tables, and then determine the tidal ranges. By analyzing tidal curves over a month, students will be able to explore the influences of the sun and moon. Students will predict the tidal curves during perihelion (around January 2) and aphelion (around July 2). The causes of seasons will be reviewed.

The gravitation pull of the moon or sun is the mass ratio multiplied by the cube of the distance ratio. For M(sun) = 2 x 10^30 kilograms, M(Moon) = 7.4 x 10^22 kilograms and d(moon) = 380,000 kilometers and d(sun) = 150 million kilometers.

(2 x 10 ³⁰)   x  (380,000)³   = 5/11 or about 0.46
(7.4 x 10²²)    (150 million)³

This information comes from FAQ About Lunar Tides http://www.itss.raytheon.com/cafe/qadir/amoont.html

Background knowledge / teacher notes:

Spring Tide- A tide which results in the greatest range between high and low tide. This tide occurs twice a month at the new and full moon.

Neap Tide- A tide which results in the least tidal range between high and low tide. These tides occur twice a month at the quarter moon.

Apogee- The moon's orbit around the earth is elliptical. During apogee, the moon is at its greatest distance (about 405,800 km) from the earth.

Perigee- During perigee, the moon is at its closest distance to the earth (about 375,200 km).

Aphelion - When the earth is farthest from the sun.

Perihelion - When the earth is closest to the sun.

From R. Hays Cummins http://jrscience.wcp.muohio.edu/lab/MoonLab.html

The seasons are caused by the tilt of the Earth's axis of rotation - the 23.4° offset of the axis from a direction perpendicular to the Earth's orbital plane. The direction of the rotational axis stays nearly fixed in space, even as the Earth revolves around the Sun once each year. As a result, when the Earth is at a certain place in its orbit, the Northern Hemisphere is tilted toward the Sun and experiences summer. Six months later, when the Earth is on the opposite side of the Sun, the Northern Hemisphere is tilted away from the Sun and experiences winter. The seasons are, of course, reversed for the Southern Hemisphere.

The solstices mark the two dates during the year on which the Earth's position in its orbit is such that its axis is most directly tilted either toward or away from the Sun. These are the dates when the days are longest for the hemisphere tilted toward the Sun (where it is summer) and shortest for the opposite hemisphere (where it is winter).

Provided by George Kaplan, U.S. Naval Observatory. Available:

http://aa.usno.navy.mil/AA/faq/docs/seasons_orbit.html

Lesson Description:

ENGAGE	Teacher will lead a class discussion: (Show students a newspaper with the tidal and lunar information) Why do the newspapers publish the time of tides? Why would people be interested in knowing the time of tides and the phases of the moon?
EXPLORE	Have students choose different tidal locations from Tide Predictions At U.S. Tidal Stations For The Next Year. Available: http://www.co-ops.nos.noaa.gov/tp4days_old.html Using the tidal heights that occurred during a month, students will generate a tidal curve and examine the monthly tidal range. How does the tidal range change during a month? Students will compare the phases of the moon to the changes in the tidal range. Visit Phases of the Moon. Available: http://aa.usno.navy.mil/AA/data/docs/MoonPhase.html Why are the tidal ranges largest during a new and full moon and smallest during the quarter moons? Teacher will identify tides that occur under a full and new moon with the largest tidal range as Spring Tides. Tides that occur during the quarter moons with a small tidal range are Neap tides. Education Elements: STUDENT ACTIVITY This NASA site contains a student activity on timing the tides. http://topex-www.jpl.nasa.gov/education/activities/ts2siac3.pdf
EXPLAIN	Journal Write: using the tidal curve, students will describe the relationship among the moon, sun and tides. Students will diagram the locations of the moon, sun and earth during Spring and Neap tides. Adaptive strategy: Develop the diagrams with the students.
EXTEND	This is a good time to review seasons with the students. Students could read the short article at MSNBC http://www.msnbc.com/news/251727.asp?cp1=1#BODY and discuss the causes of seasons. There is a diagram illustrating solstice and equinox at MSNBC http://www.msnbc.com/news/251727.asp?cp1=1 Using a diagram of the moon and earth’s orbit around the sun, ask students to hypothesize how the tidal range will change when earth is closest to the sun (perihelion), and when the earth is farthest from the sun (aphelion) Students will compare tidal curves during perihelion (around January 2) and aphelion (around July 2). How does the tidal range vary during the year? Yes, when the earth is closest to the sun (perihelion), the tidal ranges will be enhanced, and when the earth is farthest from the sun (aphelion), the tidal ranges will be reduced. Explanation of Tides. Available: http://www.pactide.noaa.gov/tide-explanation.htm GT: Using the tidal curves compare diurnal, semidiurnal and mixed tides. Information on these tidal patterns can be found at Diagrams of diurnal, semidiurnal and mixed tides Available: http://www.bigelow.org/virtual/tidetypes.gif Geographical Distribution of Tides Available: http://www-ocean.tamu.edu/~wormuth/tides/globaltidalpatterns.gif
EVALUATE	Journal Write: Students will generate a systems diagram incorporating all of the factors responsible for creating tides. Adaptive strategy: Discuss and list the factors that should be included in the systems diagram.