This time of year the sun is always low, and even fingerprints or linty dust on a canopy’s inner surface greatly reduce visibility.  For this reason it pays to be extra tidy about clean canopies during winter months.  Scratches can render a canopy opaque in low sun, so winter is a good time to polish those out, too.   Be careful though, and use only clean, soft plastic.   Never use ordinary paper towels  - they can cause scratches!