def Daylength(day):
        if Daylength_checkbox and day is not None:
            return day_length(day, sun_alt, sin_lat, cos_lat, sun_radius=sun_radius)

    def Refraction_Effect(day):
        if Refraction_checkbox and day is not None:
            return (day_length(day, sun_alt, sin_lat, cos_lat, sun_radius=False)
                    - day_length(day, 0, sin_lat, cos_lat, sun_radius=False))

    def Effect_due_to_Suns_Apparent_Angular_Diameter(day):
        if Angular_Diameter_of_the_Sun_checkbox and day is not None: