Think of it this way. Over the next time interval, the true UTC click ticks 10 times. Then the time becomes time+10. If the AWS clock has longer seconds and onl

Think of it this way. Over the next time interval, the true UTC click ticks 10 times. Then the time becomes time+10. If the AWS clock has longer seconds and only ticks 9 times, then the time is only time+9 on their clocks. Therefore, the time at AWS is falling behind UTC, since UTC is incrementing faster.