Auto-exposure in Coniston

I took these two photographs in exactly the same place at the same time. The camera was on an automatically adjusyed exposure time, The sky was much brighter than the foreground, In the top picture, the camera muat have sensed the darkness and gone for a longer exposure time, That meant that too much light arrived from the sunlit snow covered mountains in the distance. They merged with the sky. Pointing at the brighter sky gave a shorter exposure time and the mountains became visible. I need to look up how the light is read and then used to adjust exposure time.