In order to improve the cloud seeding reaction, the basic processes in
cloud microphysics and dynamics were critically examined. The disadva
ntage of the large temperature dependence in heterogeneous ice nucleat
ion, as well as the advantage of there being almost no temperature dep
endence of strong coolants in homogeneous ice nucleation, was pointed
out. A new horizontal seeding method using liquid carbon dioxide has b
een devised to maximize the effects of seeding, and simple devices for
airborne and ground mobile applications were developed and tested in
supercooled fogs and low-lying stratus clouds. Seeding tests revealed
the development of vertical motions of the seeded plume and associated
wind, the effective mixing of the plume with the surrounding supercoo
led fog and cloud volume, the resultant development of large crystals
and their fall, the enlargement of the initial opening, the associated
snowfall and its effects on traffic, and the accompanying optical eff
ects. The developed ground mobile fog seeding method was found to be p
ractical. A fundamental feedback reaction of the seeded plume at or ne
ar the overlying stabilization zone, which we call FILAS (falling-grow
th induced lateral air spreading), has been identified as an effective
mechanism to cause precipitation in a large fog and cloud volume. Cel
lular motions and accompanying pseudoadiabatic lapse rates were confir
med in the fog and cloud.