Standard time zones can be defined by geometrically subdividing the Earth's spheroid into २४ lunes (wedge-shaped sections), bordered by meridians each १५° of longitude apart. The local time in neighbouring zones would differ by one hour. However, political र geographical practicalities can result in irregularly-shaped zones that follow political boundaries or that change their time seasonally (as with daylight saving time), as well as being subject to occasional redefinition as political conditions change.