This type of picture is called "trampantojo",  a Spanish name, which means "deception" or "optical illusion". It's the technical term for an artwork that exists since the Ancient World. A work of art is being designed in a way that it imitates reality and leaves the beholder in a state between being amazed, doubting if up to believing that something artificial is real. A trampantojo plays with the imagination of the beholder offering a surrealistic landscape to dive into...

In this case the trampantojo is perfect if the reflection of the trees is crystal clear (which is a challenge with the omnipresent wind rippling the water) and something surprising, something unexpected appears in the "sky". To achieve a "realistic" look the pictures have been turned upside down by 180 degrees.