TYeB
Z-time (Coordinated Universal Time)
All aspects of meteorology are based upon a world-wide 24-hour clock called Zulu time (Z), more commonly called Coordinated Universal Time (UTC). You will notice all weather maps, radar, and satellite images all have their time expressed in "Z". The Zulu term stems from military usage while Coordinated Universal Time is the civilian term for this 24-hour clock.
The origin of these time zones began in the mid 1800's in England. In 1852 the Royal Observatory in Greenwich, England began transmitting time telegraphically and just three years later became the standard time in most of Great Britain. Also, charts and maps were made with reference to the observatory as the "zero" or prime meridian…
https://www.weather.gov/jetstream/time