In the Clouds

This is the first installment of In the Clouds, a new educational campaign from the DWR. You will learn about cloud seeding, the North Dakota Cloud Modification Program, and the Atmospheric Resource Board.

What is cloud seeding?

We will get into more detail about the science behind cloud seeding in an upcoming installment, but here are the basics:

Cloud seeding can be done in warm or cold weather, depending on desired outcome. In North Dakota, we do warm weather seeding, to enhance rain and suppress damaging hail.

Cloud seeding is a safe and scientific set of technologies used to enhance precipitation and reduce hail damage.

Silver iodide and dry ice are "seeded" into clouds via airplanes. They attract supercooled water droplets and aid their transition into ice crystals, which fall to the earth as rain. If the conditions are right for hail, the seeding provides more particles for the water droplets to adhere to, decreasing the size of the hail, and as a result, reducing damages.

Does silver iodide have an effect on the environment?

Published scientific literature show no environmentally harmful effect from cloud seeding with silver iodide aerosols. The silver concentration in rainwater from a seeded storm is far below acceptable environmental concentrations of 50 micrograms per liter as set by the U.S. Public Health Service. Because silver iodide is such an effective ice nucleus, it is used in very small quantities. Based on the average rate of seeding material used in North Dakota each summer, less than one-hundredth of a gram (0.01g) would be expected to fall on an acre of land during the summer project.

Cloud Seeding in North Dakota

Four counties in North Dakota: Mountrail, Williams, McKenzie, Bowman, as well as townships in Slope County, participate in the North Dakota Cloud Modification Program (NDCMP).

History of North Dakota Cloud Modification Program (NDCMP)

Cloud seeding is nothing new in North Dakota. The first seeding attempts in the state were in 1948. Once project areas were established, ground-based seeding was used until aircraft became the preferred seeding method in 1960.

The State Legislature created the ND Weather Modification Board in 1975 to provide regulatory functions, operational support, conduct research and evaluations, and provide state cost-share funding.

Counties vote to opt in to the NDCMP. The county commission then creates a 5-member "Weather Modification Authority" to oversee each county's project.

For the programs to continue, County Commissions must reauthorize their participation every five years.

Learn more about the ARB and NDCMP

Who decides which clouds are seeded?

Radar meteorologists, located at Bowman and Stanley, direct operations for cloud seeding missions. In addition to weather conditions, a number of factors play a part in the decision-making process including input from participating counties, safety criteria, radar information, pilot observations, and aircraft instrument data.

What are the goals of cloud seeding?

Enhance rainfall by helping clouds become more efficient rain producers, promoting better soil conditions for farmers.

Suppress hail by providing more particles for droplets to adhere to before falling to the ground. Smaller hail has a better chance of melting completely and is less harmful to crops and buildings.

Coming up... In the Clouds

In our next installments of In the Clouds: The science behind cloud seeding from the sky to the soil, what the studies are saying about its efficacy, and benefits for ag producers.

CONTACT: Cam Wright

camwright@nd.gov

701.328.2782