I was having a lovely wave flight at 20,000, temperature -10C (in Cowley wave airspace) and called ATC for a further clearance. No response and didn't hear any other transmissions. Tried an AWOS freq and heard nothing. Stayed within wave airspace and descended while seeking sunshine to warm up. Some considerable time later at lower altitude and warmer temperatures, I began hearing other gliders and they could hear me.

There was minimal condensation inside canopy. Perhaps some inside radio? Or something else?