
Cumulonimbus
Mammatus cloud derive their name from their pouch-like appearance.
Mammatus clouds often form on the bottom of a spreading anvil associated with a large, active cumulonimbus.
Mammatus clouds often follow, within minutes to an hour, the most active stage of a cumulonimbus. If the
mammatus are far off and not approaching, you may be spared experiencing the storm.
Mammatus are common in spring and summer. They mark a boundary between stable and unstable air. Unlike most other clouds,
mammatus clouds form in descending air! The sinking air must be colder than the environment and must contain lots of ice or liquid water. As the air sinks, it warms and the suspended particles evaporate keeping the air pocket saturated. If the sinking pouch of air remains colder than the environment, it descends below the cloud base and forms the
baglike sacks hanging from a cloud.

Cirrus (Ci) Cirrus are wispy, fibrous, white clouds that are composed of ice. They are a common cloud type that occurs in vertical motions ahead of large scale weather patterns. Cirrus clouds are associated with all weather systems. They can also be generated by flow over mountains or in regions with strong winds, such as the jet stream. They often occur as wisps aligned in the same direction and generally do not completely cover the sky. When isolated cirrus occur, they are not indicative of a weather disturbance. Cirrus clouds similar in shape to a comma are cirrus
uncinus or mares tails.