 Schlieren analysis is based on the principle that any disturbances to the surrounding air may be detected (the Schlieren effect), like the shadow cast by the sun through the steam and hot air from a hot coffee, or even the Mirage wave effect caused by the hot air on pavement on a summer day.It is essentially the reverse of Adaptive optics, rather than minimizing the effect of atmospheric disturbance, Schlieren detection capitalizes on that effect.This form of MASINT is both optical and geophysical because of the optical detection of a geophysical (atmospheric) effect.