Light is therefore color, and shadow the privation of it by the removal of these rays of color, or subduction of power;
    and these are to be found throughout nature in the ruling principles of diurnal variations.
    The grey dawn, the yellow morning and red departing ray, in every changing combinations, 
    are constantly found to be by subduction or inversion of the the rays of their tangents.

    -- J. M. W. Turner, 1818.

https://archive.org/details/colourinturnerpo0000gage/page/11...

As an artist Turner has inspired me not just with his use of colour, which was masterful, but with his readiness to break normal painting rules. We would scratch at his paintings with a specially long fingernail, stab at them with brushes, use watercolour almost like oils, do anything to get the image that he needed. We get most of this from looking at the paintings and from anecdotal evidence because as the article says he painted in secrecy behind closed doors.

His later works are truly amazing, given the time in which they were made. Many of the later images we know him for were from sketchbooks and studies, and not necessarily for sale or to be seen by others (code snippets?) but are impressionist years before that became a thing.

You can go to the Ashmolean Museum in Oxford and go to the Print Room (you have to book) and ask to see some. I'm told by a friend I've not done that.