On the summer solstice at 40 north latitude, the sun rises in the northeast. Why is the sun due south at noon and why does it run from north to south?

On the summer solstice at 40 north latitude, the sun rises in the northeast. Why is the sun due south at noon and why does it run from north to south?

Suppose there is a flagpole at 40 degrees north latitude, let's look at the direction of the shadow.

The direction of shadow is along the direction of the sun, and the opposite direction is the sun.

As shown in the figure:

At sunrise in summer, the flagpole is at point A, the shadow falls in the southwest and the sun is in the northeast.

At noon in summer, the flagpole is at point B, the shadow falls in the north and the sun is in the south.

(Click on the attached figure to enlarge. )