The ability of a muscle or muscle group to exert maximum force in a single effort is

Muscular Strength:
the ability of the muscles to exert a force. The maximum amount of force that a muscle can generate in a single effort. Muscular strength in the upper body is tested by the maximum bench press and the lower body by the maximum leg press

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun