Placing the Horizon with Gusto
A horizon line is present in most landscape images. Since it's so ubiquitous it's easy to take it for granted. But by taking control of where the horizon line falls you can not only complement your subject, you can dramatically highlight it.
A common tendency of beginning photographers is to place the horizon line in the middle of the frame, not for any real reason other than that they point the camera straight ahead when the press the shutter. It's not so much a conscious decision regarding composition as much as it is a feeling that keeping the camera level in every plane is inherently desirable and that centering the horizon helps to achieve this.
If you're photographing a mountain scene reflected in a placid lake at sunrise, the resulting symmetry of mountain above and below can work quite well with the horizon centered. There are other cases as well where the subject matter is reinforced by the central position of the horizon. These sorts of images though tend to be the exception though rather than the rule.
Most of the time, the horizon will look better when not centered. For the exact same reason why that mountain reflection looks great with the horizon centered, most other images won't. The central horizon in that placid sunrise reflection shot strengthens the impact of the image. But placed the same way in an image lacking such strong symmetry from top to bottom, it tends to compete with the subject rather than reinforce it.
To decide where best to place the horizon, first consider the relative strength of the sky versus the land in the scene. If the sky is relatively featureless and the foreground is where the interest in the scene lies, position the horizon in the top half of the frame to deemphasize the sky. If instead the sky is filled with dramatic cloud shapes and it is this that made you want to take a shot, position the horizon in the lower portion of the frame so that gorgeous sky is given due prominence.
But don't stop there.
To really emphasize the strong points of a scene, push the horizon a bit further than the natural weight of sky versus land would imply. The job of a photographer may start with creating a pleasing composition, but by why not make the best image you can? By pushing the horizon just a bit further you can often create an even better image. If you want those dramatic clouds to look even more dramatic, leave only a hint of foreground in the frame. Or if the sky has little going for it, crop almost all of it out leaving only enough to provide context to the beautiful foreground in front of you.
By being bold, you leave little ambiguity in the mind of the viewer as to what you want them to focus on. Confident choices create images that stand out. If that means centering the horizon to make the most of that mountain reflection even when most photography books advise against placing it in the center, do it anyway. But when instead you place the horizon high or low to emphasize the strongest part of an image, do it with gusto.