**PART 8 - SINE WAVES**

The wavelength
is equal to the circumference of the Earth. The amplitude of this wave,
measured from the middle of the wave (the equator), is 30° of latitude. Recall
that the 30th parallels are ½ of the height of each hemisphere, or ½ of the
radius of the Earth.

Since the height of the wave is equal to ½ of the Earth’s radius, the ratio
between the wavelength and it’s amplitude is 4π.
Measuring the amplitude from the top of the wavelength to the bottom (from 30°
N to 30° S), the amplitude is equal to the radius of the Earth, and the ratio
between the wavelength and the amplitude is 2π.