1.   Although it is not quite the highest point above sea level for the Roman wall, the remains of the wall are higher above the ground than anywhere else.

2.   Looming even higher above are special moving lights affixed to ceiling trusses.

3.   The springs are higher above.

4.   This factor takes into account the humidity on the ground and how fast the temperature of the air cools as it is measured higher and higher above the terrain.

5.   High prices last year prompted OPEC to nudge output even higher above its agreed levels.