  This paper describes the wide-field three-color observations of an expanded
field of noctilucent clouds modulated by a one-dimensional gravity wave. Long
wave crests were aligned by a small angle to the solar vertical in the sky.
This made possible separate determination of altitude and particle size at
different wave phases based on three-color photometry of noctilucent clouds.
Thereby, it is possible to use simple optical imaging to record the changes in
the parameters of noctilucent clouds when a short-period gravity wave passes
by.
