A featureless, blue sky could become (quite literally) monotonous if that were to comprise the majority of the image, but include some clouds and the story changes remarkably.  Like fire or flowing water, humans are drawn to clouds.  While there is a quasi-pattern that we recognize and like, there is also an element of uniqueness — no two clouds will look quite the same — that works wonders to draw in a viewer.  Dramatic contrasts can be achieved with clouds against the sky.  In color, there can be contrasts in tone, color, and texture, and these contrasts can be enhanced with a polarizing filter.  It is easy to over-polarize and cause the sky go distractingly dark blue or indigo; especially since going digital, my use of polarizing filters has been to find the point of maximum polarization and then back off (rotate the polarizer’s ring) by 15° to 30°.  In black & white, there can be contrasts of tone and texture, and these contrasts can also be enhanced with either a polarizing filter or a (yellow, orange, or red) contrast filter.  In digital photography, I recommend not using color filters (such as the contrast filters) on the lens, but performing such enhancements on the computer, where you have more choices and a more forgiving environment.

 

Ansel Adams made marvelous use of low horizons to capture clouds in his landscapes (for examples, do a Google image search on “Ansel Adams Clouds” (no quotes)).  Adams’ work is a great example of this technique, but certainly not the only example.  For a broader sampling, try doing a Google image search on “Photography Clouds” (no quotes) — you’ll notice a lot of examples of low horizons and even some cases of no horizons (sky only).

 

A sunset provides another opportunity to benefit from a low horizon.  The intense warm colors and gradients are an attractive subject and can warrant filling the majority of the frame.  Often, the dynamic range of a sunset is so broad that anything not in the sky will be silhouetted, and thus any foreground in a sunset should be selected carefully to make sure it makes a meaningful contribution to the overall composition.  For those using digital cameras, I recommend against using automatic white point correction for sunsets; that automatic feature, while usually quite helpful, will see the sunset colors as a deviation from normal and wrongly try to “compensate” for them.

 

In short, when the sky is interesting, lowering the horizon will enable you to dedicate more of the frame to your interesting subject.

 

The above image depicts clouds over Stanley Lake in Idaho.  McGowan Peak is often a subject unto itself from this vantage point but, on that July morning, the clouds were the more interesting story.  A wide-angle lens enabled me to capture the height and breadth of the clouds, and to place the peak along a lower horizontal line in the frame.