Terrain, Vortices and Downbursts
In a glider, there can be a sudden silence. Since my incident two years ago where I lost 285' after turning final I've heard from other glider pilots who encountered such conditions.
I suspect that many stall/spin and wire strike fatal accidents would be more correctly attributed to a low level vortex and/or downburst.
Having narrowly missed the usual misattribution, analysis of my flight recorder data revealed a vortex and downburst.