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Chapter 6

Chapter 6 Notes.docx

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Martin Ralph

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Chapter 6: Tidal and Lunar Rhythms
Two most important influences of the moon on our environment are the light that it
reflects from the sun and its influence on tides.
A complete cycle from one new moon phase to the next is completed in about 29.5 days,
the duration of which is called the lunar or synodic month.
The amounts of light reaching photoreceptors will to a certain degree, depend on how
high the moon is.
Light reflected from the moon has the same visible spectrum as sunlight.
The full moon being bluer and becoming slightly redder during the quarter phase.
Overall, the quality of full moonlight appears to be quiet close to that experienced just
after sunset.
A number of events drawn from a diverse group of terrestrial animals occur in
conjunction with moonlight. Often the amplitude of a circadian pattern is modulated by
increased or decreased activity during increasing or decreasing moonlight.
Biological rhythms are possible without the involvement of pigments. Locomotor activity
normally oscillates in synchrony with the tides – not LD cycle.
High and Low Tides
The timing and magnitude of tides depends on the position of the moon and sun, and also
on the geographic location, type of shoreline, ocean bottom, wind, and barometric
Global views of earth – two high tides and two low tides occur simultaneously.
One high tide in line with the moon, and the other on the opposite side of the earth. The
low tides are present at these times, but located 90 degrees from the high tides.
The forces of gravitational forces decrease with distance – the region of the earth nearest
to the moon is subjected to a greater attraction or pull and the waters in that area bulge
toward the moon.
A centrifugal force produces the bulge on the opposite side.
The center of mass between the earth-moon system lies within the surface of the earth
that is closest to the moon
Earth Tide
The earth itself also responds to these physical forces and results in an idea called Earth
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