Low-Level Clouds, pt. I

In this post, we'll look at three examples of one of the two types of low-level clouds: cumulus clouds. Low-level clouds, incidentally, are those clouds that have bases that start at no more than 6500 feet.
Cumulus clouds are the type of cloud that most people think of when they think of clouds. These clouds can be recognized by the "clumped" shape. (Stratus clouds, on the other hand, are smooth, as we'll see in the next post.)
The first picture is of a cumulus humilus (fair-weather cumulus). Clouds like this show limited vertical development and indicate that the atmosphere is stable, at least at the moment. These clouds are among the most beautiful.
The second picture is a distant picture of a distant cumulonimbus. Cumulonimbus clouds (also know as thunderheads, et al.) technically cannot be assigned to any given level, since they often reach up many thousands of feet. However, I've included them here since they often start at the low levels of the atmosphere. These clouds form during the summer months and are responsible for most strong and severe storms. They start life as a simple cumulus humilus, but if the atmospheric conditions are right, they will grow into the intimidating towers like the one seen in picture number two.
The final picture is of the sky on a particularly turbulent day. No rain or other significant weather occurred with them, but they are fascinating to look at. The cloud base is not smooth at all. Although I'm not 100% sure of its cause, I would guess that what happened was that right above the clouds is a layer of stability, while the air below was highly unstable. The result is that a wave-type motion developed, creating the bizarre patterns that we see.