The tilt of the Earths axis can affect where the Suns rays hit the Earth. If the northern hemisphere tilts slightly more than the southern hemisphere, the northern hemisphere is facing the sun more often, this is known as "Summer" for people in the north, and "Winter" for people in the south. Im not sure if that answered your question, but the suns rays bounce off the Earths surface and clouds and sometimes hit each other in our atmosphere.
the answer to your question is called a destructive plate boundary. this is when the more denser plate goes underneath the lesser dense plate.
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After some research and studying the graph you posted with your question, there are many reasons why all four latitudes have the same number of hours of daylight on March 20th and also September 22nd.
Some of the reasons are:
These two dates are equinoxes, the sun's direct rays are over the equator, and the Earth's North Pole is not is not tilted toward or away from the Sun on those specific dates. Any of these answers are acceptable for the question you asked.
D.) siroccos (dry dusty wind)
