119. Volumetric clouds and line-squalls.
A "line squall" (LSQ hereafter) is simply a linear series of Towering-cumulus or Cumulo-nimbus clouds, (going up to 60'000 feet or more) associated with a low cloud-base and very heavy rain, making observation of events within the line squall very difficult for surface vessels, and all but impossible for aircraft to penetrate (for reasons I'll not go into). LSQ's can occur over distances from 5 miles to 500 miles, and usually of 5-100 miles width! LSQ's not infrequently occur over the sea, and are a hazard to shipping owing to the very strong winds and rough seas associated with them, as well as very confused seas as they often occur in conflict with, or in combination with more widespread wave action. They feature heavily in reports of naval actions, as for the last hundred years or so they've been used as a means of sheltering from observation and therefore also gun-fire or aerial attack. "Volumetric cloud" simply means modelling these essentially as a 3d object, and likewise the heavy-rain periodically associated with them, rather than simple as a visibility distance or 2d representation.
Why do this? At some point there may be radar-equipped, or radar-directed, anti-submarine aircraft. The LSQ's provide a strong refuge from such aircraft, as no pilot in his right-mind would fly under one, even under orders. The reduced visibilty in one, as well as very heavy rain on the plexiglass of the aircraft would make visual acquisition of a surfaced u-boat all bar impossible at any range. They would also confer a good axis of attack seeking to close submerged, as the escort's hydrophones would be swamped by the noise of millions of gallons of rain striking the surface of the sea. So, the existence of the LSQ allows for variation in the visibility/detection-ranges for aircraft and escorts, subject to where the LSQ is, where the convoy is, where the escorts and aircraft are, and where the u-boats are thus presenting a more interesting "battle-field" where sometimes the weather can be exploited tactically - or where it sometimes acts as an obstacle.
For example, seeing the convoy to take observations would be all but impossible if the LSQ cover the u-boat, or, intervenes between convoy and u-boat. This potentially has other interesting implications, such as 1 u-boat being unable to take observations despite being what would normally be in easy visual range, and having to gain observations from other u-boats to be able to plot an optimal course so as to intercept the convoy the other side of the LSQ...
LSQ's are just as likely in darkness, as daylight, but can usually be readily spotted, as the clouds are internally-lit periodically by lightening within during the hours of darkness. As the energy driving them is caused by cold-air over a relatively warmer sea, rather than the usual solar-heating of land in the case of thunderstorms we're used to, they remain energetic even in the hours of darkness.
Anyway, as they could provide advantages and difficulties for both sides, and the convoy may be routed at any angle relative the LSQ, they could well serve to provide some interesting tactical situations, visually arresting sights, opportunities and dangers, I think they're well worth being an occasional and random treat! (rather than a lobby configurable setting). They also become more interesting when one thinks about a radar-equipped escort suddenly appearing out of the heavy-rain, or, in the years before radar, a u-boat employing one as cover, to get much closer in (daylight?) than it could ordinarily get before being spotted (from within the LSQ)... Then there's implications of the locally heavy seas on whether or not PD can be easily maintained, and whether or not a Schnorkel can be employed....
So, whilst a linear - but a little irregular - set of such clouds, and the weather they engender, is at first sight, not very promising as a thing to add to the game, as one thinks about in relation to directions the game may go, in regard to aircraft, radar and later years weapons etc, then I think it's well worth some examination?
Line Squalls:
https://en.wikipedia.org/wiki/Squall_line