which of the clouds are made mostly of ice crystals?
Answers. Best Answer: The altitude and therefore, the temperature, together with the age of the cloud, decides if it is made of ice crystals, water droplets or, both. High clouds only made of ice crystals are called cirrus clouds. Those are the left-overs of strong convection bringing moisture all the way to the tropopause, which is the top of the troposphere. Sometimes, cirrus even escape from the troposphere into the stratosphere.