Scientific background for the AMS policy statement on planned and inadvertent weather modification

1. Introduction

Humans modify the weather deliberately and unintentionally; this is well founded in both observations and theory. Evidence accumulated over the last 50 years suggests that certain local weather conditions including fogs, low clouds, and precipitation in some areas can be altered by carefully controlled, scientifically founded cloud seeding. Similarly, the effects of inadvertent weather modification are becoming better understood. Cities, industrial complexes, and power plants affect local weather conditions and alter precipitation. Regional weather changes result from other human activities such as deforestation and major vehicle and airline transportation …