With that high an OG I normally leave it in primary for a month . Did you add any yeast nutrient early in primary ? <| sep |> When light passes from one medium to another it bends . Examples would be from air to water , air to glass , cold dense air to thinner hot air . Heated air rises off the ground but doesn ' t quite mix with the surrounding cold air . The light gets slightly bent through all these different constantly changing air densities and causes lights to look wavy . The more of a difference in temperature the more the light bends and the more wavy it looks . It also makes stars twinkle ! On a hot road the difference in temperature of the air can be so great that it bends the light coming from the sky back upwards into your eyeballs . That blue on the road is actually the sky !