Cumulus clouds have the following description. These low clouds have a puffy appearance that resemples cottonballs or popcorn. They frequently have flat bases with lumpy tops. With bases usually ranging from near the surface to about 6,500 feet, these clouds form in air rising from heated areas on the ground.

Lenticular clouds have the following description. These lens-shaped clouds typically form at middle levels. They are usually associated with strong winds blowing over mountainous areas. The mountains cause a pattern of up and down waves in the wind, with these clouds forming at the peaks of these waves. Often, they will form in the wave capping a prominent mountain peak, but can also form in the subsequent wave crests in the lee of the mountain.

Altocumulus clouds have the following description. These middle clouds typically display a patchy, cottonball appearance. These clouds arise from unstable middle-layer air masses. The bases of these clouds are usually found around 6,500 to 23,000 feet.

Nimbostratus clouds have the following description. Often called rain clouds, these clouds exhibit a uniform dark gray appearance. Their bottoms are typically blurred and indistinct due to falling rain or snow. These clouds have low bases, but may have considerable vertical development bringing the tops into the middle level range.

Cirrus clouds have the following description. These high clouds are composed almost entirely of ice crystals. They display a whispy, feathery appearance. Their base altitudes typically range from about 16,500 to 45,000 feet.

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