“While it is true that values and tonality are linked (a painting whose values are incorrect will not have a true sense of tonality), value can be demonstrated in a black and white photo, for example. Tonality cannot be demonstrated by any photo; it is the very color quality of light, shimmering, twinkling, changing — think veils — that envelops and surrounds everything.”
— Jerry Fresia The Importance Of Atmosphere In Plein-Air Painting
Tonality is one of those “the more you learn, the more you see it” things that make painting so rewarding and so frustrating. It takes patience to get to the lightbulb moment when it all falls into place, when rather than merely knowing it exists you’re indeed seeing it. (It can feel a bit like being with a group of birdwatchers all enthusing about a bird you can’t see no matter how hard you try and how much someone else points you towards it.)
Around sunrise and sunset, you can get what photographers call the “golden hour” when everything is covered by a warm, red-gold light. This is probably the easiest time to see tonality, light having a colour, because it’s so strong. Especially in the greens in the landscape, which shift towards yellow-green rather than blue-green.
For me the lightbulb moment seeing a purple shadow on a boabab tree near sundown. On the frosty February morning when I took the photo below that memory came back to me because of the blues in the colours where the grass tufts cast shadow. Part of the colour difference is of course because the weak winter sun had been up long enough to melt some of the frost but not where the grass tufts had cast shadow. I stood here for quite some time contemplating yellow, blue, and green. I should have sketched, but my fingers were too cold.