Two Approaches for Studying Cold Pools in Shear

This presentation reviews two approaches for studying cold pools in sheared environments.  One approach requires a rigid upper boundary in close proximity to the cold pool.  As environmental shear increases, the leading edge of the cold pool becomes steeper, approaching nearly 90 degrees (relative to the surface).  Near-surface environmental air always ascends farther as shear increases, and is always swept over the top of the cold pool.  The second approach places the rigid upper boundary far away from the cold pool.  As environmental shear increases, the leading edge of the cold pool becomes steeper, and can exceed 90 degrees (i.e., cold pool edge leans over environmental air).  Near-surface environmental air ascends to greatest height for an intermediate shear value;  with weaker shear, environmental air is swept over the top of the cold pool;  with stronger shear, near-surface air separates from the cold pool and environmental air essentially overturns.  A comparison to observed squall-line structure will be made, which suggests that the second approach better matches behavior in nature.