How do we define time globally?

longitude and latitude grids mark the globe for points of reference to the foot in degrees. then the globe is divided with alphabetical letters starting with a in greenwhich or 0000hours then moves around the globe from the 0 hour to the right until it reaches one hour before itself itself 2400 later so each zone is assigned a letter of the alphabet a-b-c and the hour is in conjunction with the letter so a=0 b=1 c=2 and so on until x is 2400

Explanation:

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.