"This altitude change of a given pressure surface as one moves poleward is in response to generally average temperatures in the underlying air columns, between the constant pressure surface and Earth’s surface."

Lower

Explanation:

A pressure surface is an atmospheric surface where everywhere along that surface the pressure is equal. The surface pressure over that area is directly proportional to the air mass

Change in air pressure at a given locality often indicates a change.

Increases in air pressure do not apply exclusively to altitude. At the surface of Earth, small but significant pressure fluctuations are related to the strength of the insolation.

Lower

Explanation:

Air pressure drops as you move to higher altitude ie towards the poles.

What this means is that atmospheric pressure decreases with increasing height. Because most of the atmosphere's molecules are held close to the earth's surface by the force of gravity, Air pressure then to decrease rapidly at first, then more slowly at higher levels. as you move up in altitude, there's less air above you pressing down, and thus the air is less dense & at lower pressure, until finally in space there's none at all.