Mature Stage

When the cumulus cloud becomes big, the water in it becomes heavy. It starts to fall out of the cloud. At the same time, cool dry air starts to enter the cloud. Cool air is heavier than warm air. The cool air creates a wind that blows downward. This wind pushes the heavy water to the ground. It starts to rain.

This cloud is now called a cumulonimbus cloud. Lightning and thunder start to occur. The cumulonimbus is now a thunderstorm.

Mature Stage

When the cumulus cloud becomes very large, the water in it become large and heavy. Raindrops start to fall through the cloud when the rising air can no longer hold them up. Meanwhile, cool dry air starts to enter the cloud. Because cool air is heavier than warm air, it starts to descend in the cloud (known as a downdraft). The downdraft pulls the heavy water downward, making rain.

This cloud has become a cumulonimbus cloud because it has an updraft, a downdraft, and rain. Lightning and thunder start to occur, as well as heavy rain. The cumulonimbus is now a thunderstorm cell.

Mature Stage

When the cumulus cloud becomes very large, the water molecules in it become large and heavy. They start to fall through the cloud when the rising air can no longer hold them up. Meanwhile, cool dry air starts to enter the cloud. This is known as entrainment. Because cool air is heavier than warm air, it starts to descend in the cloud (known as a downdraft). The downdraft pulls the heavy water molecules downward, making rain.

This cloud has become a cumulonimbus cloud because it has an updraft, a downdraft, and precipitation. Lightning and thunder start to occur, as well as heavy rain. The cumulonimbus is now a thunderstorm cell.