This vs that often (but not always) refers to the object’s position. This refers to an object that is close eg this glass (in front of me) is mine. That refers to an object that is further away. Eg That tree (over there) is a pine. So in this context it will (almost) always be that cloud because it is in the distance. This is somewhat flexible... but generally speaking if you say “that” you would be pointing to an object away from you.
There are other differences between the usages but I think this is the essence of it and certainly is the issue with this question.
Also, the Swedish sentence says “that” so translating to “this” would be incorrect on that level anyway!