Updrafts cause the cloud tops to grow higher and higher, sometimes as high as ten miles. High winds in the upper atmosphere sometimes cause the tops of the storm to be blown to the northeast. This is know as the anvil of the storm. The clouds underneath this anvil are generally free of rain. The rain falls to the northeast of the anvil.
Super cells form along an area of instability known as a squall line.
A squall line is an area of cooler air out in front of a cold front. This cooler air meets with the warmer air first, sometimes forming very destructive storms. A super cell is a very characteristic storm. Whereas most storms have several updrafts and downdrafts which interfere with each other, a super cell has one updraft and downdraft. This allows the storm to feed off itself, giving it a long, and intense life.