Questions about fundamental astronomy

[Primarygun]

1. Where is the sun in its ecliptic when it is the hottest period in the northen hemisphere?

2. Take a look at the picture I upoloaded.

Why is the time that the sun is at the meridian again 12:30 rather at at noon? How do you explain the wave shape of the curve?

 

I'd think that it's because the discrepancies between the sidereal day and the apparent solar day, I don't know if it is the answer

[Jacques]

12:30 because hongkong is not situated in the middle of his time zone

Sinusoidal because the orbit of the earth is an ellipse not a circle