practicality

With characters like that, it helps if there's something to work off of. As you said, someone trying to convince you otherwise or simply a circumstance that shocks the character into believing. And just because you are skeptical, doesn't mean you can't try to rationalize things in the name of science and experiments...like a geek trying to apply real world physics to Star Wars. Maybe the whale had an overdeveloped voice box? ^_^

Good luck with the snow. I hope it doesn't freeze into sheets of ice...like it did here...