The orbit of the earth is elliptical, and therefore, the season we call summer, which in the northern hemisphere takes place at aphelion (farthest from the sun), lasts longer than the season we call winter. In the northern hemisphere, winter (when we are tilted away from the sun) takes place at perihelion (nearest the sun), and is therefore shorter than summer. Like a ball rolling in a bowl, it moves faster when it is close to the center, and more slowly when it is far from the center.
However, any American school child will assure you that summer is the shortest season.
It's difficult to say because no one can decide that the time is linear or not.
Perception is everything.