Why Do Satellite Ground Tracks Oscillate in Latitude?

[hhhmortal]

Hi, I'm a bit confused on how ground tracks for satellite work.

I have noticed they orbit the Earth with a ground track that oscillates all around. Why is this? And why does the oscillation change in latitude for every pass around the earth.


Thanks.
Much appreciated.

 

[hhhmortal]

Bump^

 

[D H]

The Earth rotates underneath the satellite.