Time, as we commonly measure it, is based on the rotation of the Earth on its axis and the position of the Sun in the sky. The Earth takes approximately 24 hours to complete one full rotation, resulting in a day. However, the specific time at a given location can vary depending on latitude due to the Earth's shape and the way it moves.
At the equator, the Earth's rotation axis is perpendicular to the direction of the Sun, resulting in relatively equal day and night lengths throughout the year. In this region, the duration of daylight and darkness is relatively consistent.
As you move away from the equator towards higher latitudes (either towards the poles or away from them), the angle at which sunlight reaches the Earth's surface changes. This variation in solar angles affects the length of daylight throughout the year. Near the poles, there are periods of continuous daylight during certain times of the year (summer), and periods of continuous darkness during other times (winter). The further you are from the equator, the greater the variation in day length between seasons.
To account for these variations, time zones were established. Time zones divide the Earth into different regions, each following a standard time based on a reference meridian, such as Greenwich Mean Time (GMT) or Coordinated Universal Time (UTC). The boundaries of time zones are typically drawn along lines of longitude.
In summary, while the concept of time remains constant, the duration of daylight and darkness can vary based on latitude due to the Earth's shape and its tilt in relation to the Sun. Time zones are used to standardize time across different regions, taking into account these variations in daylight.