As the year progresses, the Earth's tilt changes to where the North Pole is pointing away from the Sun producing winter.
Try the simulation by clicking on the image on the right, that gives a clear visual representation of the annual march of seasons and the Earth’s tilt with respect to the sun plane.
The most helpful aspect is that the you can change the observer latitude to the latitude of your interest (Santiago de Compostela is at 42,9 º N), select the date on the timeline. and also observe the angle of sunlight. The amount of heat energy received at any location on the globe is a direct effect of Sun angle.