Atomic time, solar time and the two clocks the world has to reconcile

Background

This is in the news this week because the General Conference on Weights and Measures has just voted to abolish the leap second.
The world runs on two different ideas of time.
Universal Coordinated Time is generated by atomic clocks, which keep an extremely steady beat.
Solar time follows the rotation of the Earth, which is irregular and does not keep a steady beat.
Because the two drift apart, a correction was needed, and until now that correction was the leap second, inserted roughly once every one and a half years.
The replacement correction is the leap hour, to be inserted only when the two measures of time are 3,600 seconds apart.