Update on Cloud Seeding

I get asked about cloud seeding all of the time and I haven't had much new to tell people in recent years. So, I'm grateful to the Washington Post for a really interesting article on the topic. The bottom line is that it is finally proven that cloud seeding works in certain circumstances. 

Snowed-over experimental radar equipment
NCAR photo

There are two big qualifications:

• It is only proven it works in stratiform-type precipitation in mountain areas. We still don't know for certain whether it works with thunderstorms or in areas outside of mountains. 
• The increase of 3.3% is over what would have fallen anyway. In other words, if you don't have precipitating clouds, cloud seeding will not help.

Still it is a significant scientific advance to know for sure that cloud seeding works in those circumstances.