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.
source: windows to the universe