The principle is that the moisture absorption-scattering from aircraft to absorb moisture in the air and cold substances so that the moisture condensing and collected into the clouds.
The principle is the scattering material absorbs moisture from the air. To absorb humidity in the air Exposure to cold and moisture condensation and the formation of clouds.
The principle is sprinkled substance absorb moisture from the air To absorb the moisture in the air. And the use of cold so that moisture condensing and include a cloud.