This exposure was made late in the afternoon during rapidly changing light. It is an example of what Fred Picker referred to as squall light.. Here is how Fred described squall light, as he dubbed it, in a 1985 Zone VI Newsletter:
A black bright presence that arrives in a rush to announce heavy rain or high wind or a cold front coming through. Squall light, though rare, seems more frequent on summer evenings but it can appear, where I live, at any time of the year. Its effect is startling. Dark objects seem bright, somehow concentrated, as though charged with energy. Pale objects radiate light. The effect is unearthly, unsettling, exciting, surreal."