Użytkownik Andy napisał:

Is that title a result of a bad translation to English? I wonder if
"Sky Full of Thermals" was intended.
It was. The Polish title is "sky full of Żar", while Żar is
Sebastian's home airfield and one of centre mountain gliding points in
Poland. "Żar" is the name of the airfield and mountain, and it also
means "heat" in plain language. It was impossible to translate the title
perfectly.

--
Wojtuś