A scene with great contrast and dynamic range, the dilemma is what do you expose for, the highlights or the shadows. A typical scene at sunset or sunrise, where the sky is very bright, expose for the sky, the shadows are typically very dark and hold very little detail. The graduated neutral density filter can equalize or reduce the range of exposure, so highlight areas are not blow out when exposing for the shadows, conversely shadows aren’t black and devote of detail when exposing for the highlight areas.