ILLINOIS STATE WATER SURVEY
Under the hypothesis based on more massive applications of seeding material (glaciation)
the effect on precipitation is much more difficult to predict — because of opposite and
competing effects. On the one hand the dynamic (heating) effect of freezing water becomes
significant, potentially intensifying the inflow of water vapor into the storm.
If the precipitation efficiency remains the same, this should produce more rainfall.
On the other hand, after heavy glaciation of the cloud, many of the small ice crystals that are
created may be swept away, as cirrus clouds in an anvil, by strong horizontal winds at the
top of the storm — hence, less rainfall.