Cumulus

This is a photograph of cumulus clouds. Click on image for full size version (50K JPG) Courtesy of Carlye Calvin

Cumulus (weather symbol - Cu) clouds belong to the Clouds with Vertical Growth group. They are puffy white or light gray clouds that look like floating cotton balls. Cumulus clouds have sharp outlines and a flat base. Cumulus clouds generally have a lower cloud deck of 1000m and a width of 1km.

Cumulus clouds can be associated with good or bad weather. Cumulus humilis clouds generally show up on a warm summer day and are associated with fair weather. These clouds have only slight vertical growth and they are detached with lots of blue sky in between. Cumulus congestus clouds are usually associated with bad weather. These clouds grow to great heights and usually become cumulonimbus clouds. Their tops look like cauliflower heads and indicate that light to heavy showers can occur.

Here's a tip on how to know if you see a cumulus cloud in the sky. Cumulus cloud cells (the individual puffs of clouds) are about the size of your fist or larger when you hold up your hand at arm's length to look at the cloud.