New Geography in Action Junior Cycle Geography Clouds Learning Intentions
In this section, you will learn: zz about the formation of clouds and the different types of cloud.
Stratus Cumulus Cirrus
A cloud is a large collection of very tiny droplets of water or ice crystals held in the atmosphere. The droplets are so small and light that they can float in the air.
How clouds are formed
All air contains water. Near to the ground it is usually in the form of an invisible gas called water vapour. When warm air rises, it expands and cools. Cool air cannot hold as much water vapour as warm air, so some of the vapour condenses into tiny droplets. When billions of these droplets come together they become a visible cloud.
Types of cloud There are three main types of cloud and each one indicates different weather conditions:
Stratus clouds Stratus clouds occur below 2,000 m.
They look like flat sheets of cloud, and indicate an overcast or rainy day. These clouds are usually a uniform grey colour, and cover most of the sky.
They look like big fluffy balls of cotton wool. They usually mean that the weather will be nice. Sometimes they can look very woolly and bring heavy showers, especially in warm weather. These clouds are usually flat on the bottom, but have very lumpy tops. Cumulus clouds usually form alone and there is a lot of blue sky between individual clouds.
