Timekeeping architecture binds the division of the 24 hour AM/PM system to the Lat/Long system across the planet's dimensions and rotational characteristics, albeit that the 'average' designation in a 24 hour cycle interchanges with 'constant' rotation as a convenience and from there into the Lat/Long structure.

The time differences spread across 15 degrees of longitude is 1 hour and 1070 miles at the Equator hence 360 degrees amounts to the Earth's 24901 mile circumference. The interplay between the components is therefore any combination the observer chooses -

The Earth turns its 24901 circumference in 24 hours or turns at a rate of 15 degrees per hour,its Equatorial speed is 1070 miles per hour ect so that even now NASA has gotten its act together expressing this fact -

http://image.gsfc.nasa.gov/poetry/ask/a10840.html

The Lat/Long system overlaid on the geographical structure of the Earth is not arbitrary in a sense that it is a consequence of the 1461 rotations it takes to complete 4 annual circuits and the average rotation within each of these cycles. What gets 'averaged' out is the orbital surface rotation component which causes the natural noon inequality when combined with daily rotation hence it allows the assumption that rotation is constant within the two surface rotation combination. This is perhaps the most intricate element of the architecture but it is made all the easier when the observer affirms that aside from and in addition to daily rotation,all locations on Earth turn once to the central Sun.

I have seen many variants of the celestial sphere mob try to justify a framework that is outside the 24 hour and Lat/Long system like some kind of self-mockery -

http://www.universetoday.com/26623/h...-earth-rotate/

I took my cues from participants in this forum over the years that rather than adapt to and adopt the productive architecture of timekeeping and the cyclical references that not only go into creating them but also the limitations that organizations act in similar fashion by digging a bigger hole rather than letting visual imaging,graphics,experience and common sense do the work.

Students and interested adults need to know why one 24 hour day and one rotation of the planet are one and the same and the encompassing reasoning that makes it that way.