The cavities in the northern cap are all accounted for by the airlock systems.

We are on the northern cap.

As for the other physical operations, the black snow algae is on the northern polar cap, and can't be removed.

But the northern cap has not been adequately studied yet, and the data from the southern cap are inconclusive.

The train's hum increased in pitch and they plunged into the fourth chamber's northern cap.

Between the rivulets on the glass, through a trench-like break in the clouds, Patricia saw the opposite northern cap.

The northern cap seemed to be obscured, not nearly as obvious as the looming gray presence in the other chambers.

A breeze from the northern cap pushed through the outskirts of the third chamber city, rustling the nearby trees.

As the craft banked, the window filled with the austere grayness of the northern cap.

The northern cap shattered, but there was no outpouring of molten rock; the air in the chamber abruptly clouded over.