Final answer:
The question contains a possible error since 'space' doesn't relate to the given words or seasons. Instead, the difference between summer and winter is mainly due to the changing length of days and the angle at which the sun's rays hit the earth. Near the equator, this results in a 'wet season' and a 'dry season' rather than distinct seasonal changes.
Step-by-step explanation:
Regarding the signs SUMMER, UGLY, and DRY, the question seems to have an error as 'space' does not directly relate to these words or the concept of seasons. However, if we focus on the concept of seasons, a significant difference between summer and winter is the length of the days. Near the equator, this length doesn't change considerably, leading to a lack of distinct seasonal changes like those experienced in temperate regions. Instead, equatorial regions may experience a "wet season" and a "dry season". During summer, the Sun's rays strike the hemisphere more directly than in winter, thereby heating the ground more effectively.
At the equinox, day and night are of equal length, which is the origin of the word 'equinox'. The boundary AB mentioned in the given reference likely refers to the dividing line between daylight and darkness on Earth. The position of this boundary changes throughout the year, contributing to the seasonal differences experienced across the planet.