(note: excerpt from The Weather Modification Association site)
The Weather Modification Association (WMA) was organized in 1950 to cultivate a better understanding of weather modification techniques, impacts, and expectations among program sponsors, program operators, and the scientific community, and to promote ethical professional conduct and a free exchange of information.
Weather modification can be both planned, as is the case in cloud seeding (cloud modification), or inadvertent, for example, when pollution affects visibility. (image at right example of cloud seeding process, from water.utah.gov, click image for detail)
Planned (deliberate) weather modification is also commonly known cloud seeding, cloud modification, and atmospheric water management.
The WMA fields a wide variety of inquiries, from domestic and foreign governmental agencies, to the student doing a report for the classroom.