What determines time zones across the globe?

Time zones across the globe are primarily determined by longitude. The Earth is divided into 360 degrees of longitude, and each time zone typically spans 15 degrees, corresponding to one hour of time. As the Earth rotates, different longitudinal areas experience daylight and darkness at different times, which necessitates the division of the world into time zones.

Longitude lines are vertical lines that run from the North Pole to the South Pole, and they help in defining where one time zone ends and another begins. For instance, when it is noon at the Prime Meridian (0 degrees longitude), it is 1 PM in areas situated 15 degrees east of the Prime Meridian and 11 AM for those situated 15 degrees west.

While latitude, altitude, and temperature can affect climate and daylight patterns, they do not play a direct role in establishing time zones. Thus, the correct understanding of time zones lies in the significance of longitudinal divisions and how they relate to the Earth's rotation.