Before revision: Colored schlieren image of the thermal plume from a burning candle, disturbed by a breeze from the right Schlieren (; singular: schliere, meaning "streak") are optical inhomogeneities in transparent medium that are not necessarily visible to the human eye.
After revision: Colored schlieren image of the thermal plume from a burning candle, disturbed by a breeze from the right Schlieren are optical inhomogeneities in transparent medium that are not necessarily visible to the human eye.