You won't find too many a landscape that doesn't contain a certain amount of sky in it. Some with a little, some with a lot. The amount of sky would depend on how interesting it looks on the day, and how much impact it will have on the overall scene.
You may have seen landscapes of the great Australian Outback, or Monument Valley in Utah, USA, depicting red sandy deserts with wide, deep blue, cloudless skies and very little else.
To the viewer, these images show the isolation and the emptiness of these great lands and they do that very well on a tourism point of view, but throw into the foreground some interesting rock formations and a few wispy clouds in the sky and you instantly add character and interest to the image.
Generally, if the sky is featureless, don't use it. It will become negative space and provide less room in the scene for more important subject matter.
When you are out looking for that great landscape shot, give the sky as much consideration as you do the land. You'll find the best time for this sort of image, is in the early hours of the day, when the air is fresh and clean, especially following an overnight rain.
When you photograph the sky, you will need a good wide angle lens somewhere in the 20 - 45 mm range, if you want to get it all in, so to speak. It is best to include a little bit of land at the bottom of the frame, as this will give your image a base to sit on, but with the bright sky in the early morning, this little bit of land will probably appear quite dark, so try not to include too much of it, then your camera can meter for the sky alone.
A polarising filter would be a handy gadget to take along with you, as it really enhances blue skies and will emphasise the whites in clouds, but while using it on the wider end of the lens, you may encounter some vignetting. (darkening in the corners of the image) For more information on these and other filters see my chapter on "Filters" .
Let's say you have found an interesting sky to photograph, what can you use to add interest in the foreground? How about a silhouette? There are any number of subjects you could use; fences, windmills, dead trees, light houses, palms, grave stones. Just look around you and use a bit of imagination.
There are many types of clouds that will help you produce a stunning and memorable photograph. They include the ever-changing shapes of high strata, cirrus, or jet stream cloud. Excellent just before sunrise and especially if you have a bit of low, dark, scuddy cloud to add some extra interest to the lower part of the scene.
Cumulonimbus, or storm clouds, can make very dramatic looking images. For a good glimpse of these, visit Extremeinstability.com "Great storm photos!"
The anvil, or thunderhead of storm heads can sometimes glow pink and/or orange in the early evening, as they reach up to incredible heights and can continue to glow well after the sun has gone down over the horizon.
Lightning can also be fun to photograph, if you are able to be in an open area, sheltered from the rain, of course.
For greater impact, it is done best at night. You will need a tripod for this and a cable release (remote shutter release) and a wide lens.
You will also need to have the ability to set your camera manually on the "B" setting and set your camera's aperture to about f8 of f11.
Point the camera in the direction of the approaching storm and manually set the camera to the above settings. Using the cable release, open the shutter and lock the switch, allowing the shutter to be left open. You can close it again after the first lightning strike, or keep it open to get several strikes on the one frame. Be sure to take extra batteries with you, as they are likely to run down fairly quickly using the camera this way.
The sky is the limit. Go and take advantage of what it has to offer. But at least wait till morning! See also photographing "Lightning Strikes"
I took this in the very early days. I can now see things that I could have done better, but I thought I'd include it here to show you the colours of early morning. I suppose I could include it as an example of what not to do. For instance, the horizon line is right bang in the centre and I straightened that up whilst cropping. Anyway, it is colourful, even though the composition could have been better.