Clouds Evaporation – the process by which water molecules in liquid water escape into the air as water vapor. Condensation – The process of water vapor turning into liquid water. Dew point- The temperature at which condensation begins. Scientists classify clouds into three main types based on their shape: Cirrus, cumulus, and stratus. Cirrus Clouds- Have feathery “hooked” tales called mare tails occasionally. Cirocumulus clouds look like the scales of a fish, so called a “mackerel sky”. Cumulus Clouds- Cumulus clouds that are not very tall usually indicate fair weather. These clouds are common on sunny days and known as “fair weather cumulus”. Towering clouds with flat tops are called cumulonimbus clouds and often produce thunderstorms. Nimbus means rain. Stratus Clouds- As stratus clouds thicken, they may produce drizzle, rain, or snow. They are then called Nimbostratus clouds.