Sunny days are lovely to walk around in, but terrible for waterfall photographs. Bright, overhead, midday sun is the worst time to shoot a waterfall, as you can see in the image below. The dynamic range between the brightest highlights and deepest shadows is so vast that it’s impossible to retain all the detail, even if you blur the water. Overcast conditions (and hence a much smaller dynamic range) make for a much clearer waterfall shot. You can see the patterns in the water as it rushes over rocks, and the rocks themselves are more pleasing to look at, because while their texture remains, their harshness is alleviated by the softer water.