October 15, 2019 | Published by

Picture: Aircraft passes cloud Credit: Daniela Avila (Unsplash)

Turbulence caused by thunderstorms is a significant hazard to aviation, but we have an incomplete understanding of how it forms and where it will occur, especially outside clouds where aircraft can encounter turbulence unexpectedly.

This research uses commercial aircraft data and high-resolution simulations to study a case in 2005 over the United States where severe turbulence was encountered about 50km away from a large mesoscale convective system. Of relevance, current aviation turbulence avoidance guidelines recommend avoiding storms by 32 km (20 miles).

The researchers demonstrated this unusual case could be explained by a large amplitude atmospheric gravity wave that was generated by storm, which then amplified and ‘broke’ in the region of the turbulence encounter. This case offers further evidence of the importance of gravity waves as a source of turbulence and highlights inadequacies in current turbulence avoidance guidelines.