of a Cloud
When the number of droplets becomes so dense that the cloud looks gray or black in color, it will probably produce precipitation. The cloud becomes darker in color because the water droplets are so dense that no light gets through.
Types of Clouds
The variety of cloud types not only makes them enjoyable to watch but, in fact, they can provide useful clues to the weather ahead. As you walk out your front door each day, take a quick survey of cloud types to prepare for the day’s weather. In general, small, white, thin cirrus clouds usually mean that snow or rain is unlikely, while large, dark cumulonimbus clouds mean that a storm is looming.