Does it bug anyone else when the similes don't hold water?

I was standing on the bridge this morning and a phrase popped into my head—'the radar screen looked like a murky aquarium.' But that's wrong. Radar echoes don't drift or gleam. Nothing out there is transparent. I spend all day reading weather patterns and it's guesswork wrapped in pretty language. Why do we reach for wrong pictures instead of just saying what we actually see?