To curve outward past the normal or usual limit
Visit the Grand Canyon, travel to Scotland, hot air balloon ride.
The balloon is inefficient because of its levity; the flying creature is efficient because of its weight.
Also I began to make balloon ascensions.
The balloon in a calm can only rise and fall in a vertical line.
Some of the earliest balloon observations made the gradient increase with the height, but such a result is now regarded as abnormal.