Wall Clouds

• Wall clouds are a lowering of cloud base at low levels in the storm
• Wall clouds are a visible manifestation of the mesocyclone at low levels, in other words, the wall cloud contains significant rotation
• The tornado often forms from within the wall cloud, with the funnel cloud descending to the ground
• Here is a wall cloud at low levels from which a funnel cloud is descending
• How the tornado forms is still a mystery....., but what do we know about tornadoes???

photos by N. Atkins