The BEST Earth-Based Sites for Modern Large Astronomical Telescopes, Which

Multiple Choice

The BEST Earth-based sites for modern large astronomical telescopes, which provide the least seeing effects on astronomical images, are

A) near large cities, where the warm air from human activity serves to stabilize the overlying atmosphere.
B) at sea level, where the air is less turbulent.
C) on the downwind side of mountain ranges, where smooth airflow produces clear air and stable images.
D) on the tops of high mountains, above a large fraction of the disturbing atmosphere.