Rock-Hard updrafts?

[Melanie Kern-Favilla]

Can someone tell me the dynamics that happen in a cloud that causes some updrafts to be stout, rock-hard updrafts (and continue to remain that way) with a cauliflower appearance, as opposed to others which start out looking good, but then become sorta 'mushy' and soft? Is it evaporation? What causes that soft appearance of an updraft that started out as promising? Thx...

 

[ahaberlie]

Glaciation.. at the very top of the storm when air stops rising it spreads out.. when the edges become less defined it means the storm/updraft is no longer getting the fuel at the surface and will probably die out as it cuts off its own source of energy by quashing the surface updraft (rain, microburst, otherwise).. happens when updrafts aren't vigorous or the winds aloft don't carry the rain away from the updraft.

Good, well defined, updrafts have a healthy source of fuel from the surface (for the time being) and can actually propagate themselves when cold downdrafts away from the updraft interact with warm air at the surface and can actually strengthen the storm using its own precipitation.. requires either forward(relative to storm motion) shear (supercells) or "backwards" shear (derecho)

Here is a diagram of a typical thunderstorm ("quickly" glaciating)

Notice the rain falls basically straight down into the updraft... tilting caused by wind shear can prevent this and is necessary for well defined updrafts/severe storms.

 

[Jeff Duda]

I always thought rock-hard updrafts were caused by a strong updraft with little detrainment occurring below the anvil, and no other clouds to block the view. I didn't think rock-hard anvils were technically anything special other than what usually occurs in strong updrafts.

 

[Shane Adams]

Put simply, rock hard updrafts have what they need (instability) and plenty of it for long durations. The "harder" the updraft, the more intense/fast the vertical velocity within it is. Often times later in the typical Spring/Summer storm season, a lack of substantial directional wind shear can be made up for by extreme instability, which can increase the overall rotational potential by providing added speed to vertical air motions within the updraft before/as it's stretching the horizontal rotation created by wind shear.