Most clouds are associated with weather. These clouds can be divided into groups mainly based on the height of the cloud's base above the Earth's surface. The following table provides information about cloud groups and any cloud classes associated with them. In addition, some clouds don't fall into the categories by height. These additional cloud groups are listed below the high, middle, and low cloud groups.
* The cloud heights provided in this table are for the mid-latitudes. Cloud heights are different at the tropics and in the polar regions. In addition, a few other cloud types are found in higher layers of the atmosphere. Polar stratospheric clouds are located in a layer of the atmosphere called the stratosphere. Polar mesoshperic, or noctilucent, clouds are located in the atmospheric layer called the mesosphere.
How Clouds Form
CMMAP - Studying Clouds and Climate
Clouds in Art
Cloud Image Gallery
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The high cloud group consists of Cirrus, Cirrostratus, and Cirrocumulus clouds. High clouds are made of ice crystals due to the cold air in the upper sky. The base of a high cloud above the surface can...more
Noctilucent clouds (NLC’s) or polar mesospheric clouds (PMC’s) are found very high in the Earth's atmosphere. They are called Polar Mesospheric Clouds when they are viewed from space, and are referred...more
Cirrus clouds are the most common of the High Cloud (5000-13000m) group. They are composed entirely of ice and consist of long, thin, wispy streamers. They are commonly known as "mare's tails" because...more
Cirrocumulus clouds belong to the High Cloud group (5000-13000m). They are small rounded puffs that usually appear in long rows. Cirrocumulus are usually white, but sometimes appear gray. Cirrocumulus...more
Cirrostratus clouds belong to the High Cloud (5000-13000m) group. They are sheetlike thin clouds that usually cover the entire sky. The sun or moon can shine through cirrostratus clouds . Sometimes, the...more
The middle cloud group consists of Altostratus and Altocumulus clouds. Middle clouds are made of ice crystals and water droplets. The base of a middle cloud above the surface can be anywhere from 200...more
Altocumulus clouds are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part of the cloud darker than the other. Altocumulus clouds usually form in groups and are about...more