‘Cloud seeding’ to encourage rainfall ‘not as effective as thought’

WASHINGTON - New research from Tel Aviv University has revealed that the practice of cloud seeding with materials such as silver iodide and frozen carbon dioxide may not be as effective as thought.

During the course of his study, Prof. Alpert and his colleagues looked over fifty years’ worth of data on cloud seeding in a target area over the Sea of Galilee in the north of Israel.

“By comparing rainfall statistics with periods of seeding, we were able to show that increments of rainfall happened by chance,” said Alpert.

“For the first time, we were able to explain the increases in rainfall through changing weather patterns” instead of the use of cloud seeding, he said.

Most notable was a six-year period of increased rainfall, originally thought to be a product of successful cloud seeding - which Alpert and colleagues said corresponded with a specific type of cyclones, which are consistent with increased rainfall over the mountainous regions.

The researchers concluded that changing weather patterns were responsible for the higher amount of precipitation during these years.

The only probable place where cloud seeding could be successful, Alpert said, is when seeding is performed on orographic clouds, which develop over mountains and have a short lifespan. In this type of cloud, seeding could serve to accelerate the formation of precipitation.

The findings were recently reported in Atmospheric Research. (ANI)