Passengers on a Delta flight from Utah to Amsterdam found themselves diverted to Minneapolis-St. Paul International Airport Wednesday night after severe turbulence prompted an emergency landing.

Their plane took off from Salt Lake City Wednesday afternoon. About an hour into the flight, they ran into turbulence that caused the plane’s altitude to drop about 1,000 feet within a minute – according to the flight-tracking website, FlightAware.

Delta said 25 people on board were injured. They were taken to hospitals after landing.

We wanted to know more about what causes severe turbulence. Kwasi Adjekum is professor of aviation and aerospace sciences at the University of North Dakota. He spoke to Minnesota Now guest host Chris Farrell.