Highland Climate Festival Nature-Connection Activities

Learn About Clouds

Clouds are made up of very light water droplets or ice crystals that are suspended in the air. When warm air rises, expands and cools, it forms clouds. White clouds are formed when the water droplets or ice crystals reflect the sunlight and dark or grey clouds are formed when light is scattered rather than reflected.

The World Meteorological Organization classify clouds by altitude and divide the troposphere (the lowest level of the atmosphere, extending from the Earth’s surface to the lower boundary of the stratosphere at a height of 6-10 km) into three levels:

Low Level Clouds:              Less than 6,500 feet
Mid-level Clouds:               6,500 to 23,00 feet
High-level Clouds:              16,500 to 45,000 feet

The main types of clouds are cumulus, cirrus, stratus and nimbus.

Cirrus Clouds

Cirrus clouds are the thin, wispy clouds seen high in the sky. They look as if someone took a cloud, stretched it, pulling pieces off, like a cotton ball when it is pulled apart. They are thin because they are made of ice crystals instead of water droplets. A blue sky and a few cirrus clouds high in the sky, usually means it is going to be a nice day.

Cumulus Clouds

Cumulus clouds are the puffy clouds that children usually draw that are usually scattered throughout the sky. In Latin, the word cumulus means pile. Just like when we say “accumulate,” it means things pile up. This type of cloud is formed on sunny days when warm air rises carrying water vapor with it by evaporation. Cumulus clouds can be white or grey. White fluffy clouds mean no rain, but when they form into dark or grey clouds, it is going to rain.

Stratus Clouds

Stratus clouds look like a huge thick blanket covering the sky and are the lowest forming. These clouds are a sure sign of rain if it is warm and snow if it is cold. If stratus clouds are near the ground, they form fog or mist. These clouds form when the weather has been cold and warmer moist air blows in. The amount of moisture in the air and the difference between warm and cold air determine how thick the cloud or fog is.

Nimbus Clouds

The word nimbus means a cloud that already has rain or snow falling from it. These clouds are dark and seen during a thunderstorm along with thunder and lightning. They can be a combination of two clouds, like a cumulonimbus (thunder clouds), which means a puffy black cloud with rain falling out or it, or a nimbostratus, which is a dark wet blanket with rain falling out of it causing a ragged base.

You can find out more about different clouds from the Met Office.