Cumulus clouds are a type of cloud

Cloud

A cloud is a visible mass of liquid droplets or frozen crystals made of water and/or various chemicals suspended in the atmosphere above the surface of a planetary body. They are also known as aerosols. Clouds in Earth's atmosphere are studied in the cloud physics branch of meteorology...

 with noticeable vertical development and clearly defined edges. Cumulus means "heap" or "pile" in Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

. They are often described as "puffy" or "cotton-like" in appearance. Cumulus clouds may appear alone, in lines, or in clusters. Cumulus clouds are often precursors of other types of clouds, such as cumulonimbus, when influenced by weather factors such as instability

Atmospheric instability

Atmospheric instability is a condition where the atmosphere is generally considered to be unstable and as a result the weather is subject to a high degree of variability through distance and time...

, moisture, and temperature gradient.