Rainmaker raises $100 million for cloud-seeding drones

Rainmaker, a weather-modification startup that seeds clouds to generate rain and snow, has raised $100 million in Series B funding. Its custom drones release silver iodide into clouds; August test flights in Alaska's Kenai Peninsula produced 19 million gallons of precipitation in three hours, and the company ties its flights to 145 million incremental gallons of freshwater.

• $100 million Series B brings total funding to $150.3 million
• Drones release silver iodide to trigger precipitation
• Alaska tests yielded 19 million gallons in three hours
• Company links flights to 145 million gallons of freshwater