At first glance this image looks like a rather boring aerial photo of western Kansas. But the sky is queer, with rectangular clouds. Actually, the sky is a chunk of land from Google Earth, desaturated, cooled and flipped. It illustrates the similarity between land and sky in that each follows the rules of perspective, diminishing and flattening as field or cloud approach the horizon.
A one point perspective grid using a diagonal vanishing point can be the basis for any simple landscape view. Not only clouds, but roads, rivers and ocean waves can be worked out over such a grid. Actual scale is unnecessary in such a grid; just mark off a horizontal line, connect each mark to a central vanishing point, and a diagonal will mark the receding horizontals at the intersection points.
Of course the grid is simply a general framework to keep the image believable. Clouds vary in size and shape. They may be lined up in some orderly manner, or they may be scattered willy-nilly over the sky. The ocean might have regular waves near the shore, but complex weather conditions can form chaotic waves in mid ocean.
Undeveloped land is often a Jackson Pollack abstract of meadows, trees, lakes and rivers, which have only a passing acquaintance with a perspective grid; but the grid still rules in perspective. The balance between rules and free expression is the foundation of our perception of reality, and is also the basis of realistic art.
If you are dealing with natural land and sky forms a strict grid is a waste of time. The rough perspective that gives any landscape painting a sense of reality can be expressed with simple sketched lines. The serpentine mirrored lines above suggest a vista without any detail or effort.
A seascape such as the sketch above is essentially a cloud study. Many artists have sketched clouds, and I long ago promised myself that I would dedicate my retirement years to the subject. I imagine that the release from hard geometry and finicky detailing will be a return to childhood.
H. F. Farney, an artist of the American Indian, captured the horizontals and acute diagonals of the plains landscape in his Toilers of the Plains. Note that his clouds compliment and mirror the low sweep of the landscape; a landscape that was quite familiar to me from my early years in the Midwest.
Canaletto is famous for his views of Venice, but it is obvious that he studied the structure and moods of the sky. The Church of La Salute shows the perspective of flattening clouds at the horizon, as well as towering cumulus and color gradation across the sky. Canaletto tends to be ridiculously detailed, but also entirely believable and (appropriately for Venice) serene.
John Stobart is a contemporary marine artist and a favorite of mine. Like Canaletto he creates a perfectly reasonable cloudscape which complements the subject in terms of color, composition and narrative. His Entrance to the Chicago River Looking West in 1876 is one of innumerable examples of his skill.
This rendering of the Casa Italia at Columbia University gave me no latitude for creativity outside of the sky. I may have been a bit buzzed when I drew the clouds, because they have a curious abstract relation to a music score.
My rendering of the new town of Celebration in Florida is more conventional in its handling of sky and clouds. The most interesting aspect is the fading of the sky and clouds compared to the landscape and buildings, an effect that is typical for a sunny day with scattered clouds. Closer clouds have a certain form and volume to them, while the distance renders them flat and eventually melts them into the haze.