Saline saturated convection parcel ingestion, what would happen?

[Tom Stefanac]

Okay I need sleep but this question has been afloat in my head.

Assuming you have a supercell over the ocean or a lake with a large salt content and the supercell produced a sufficiently powerful tornado and/or inflow which lead to the ingestion of large quantities of salt water what if any effect would this have on the storm?

I imagine it would have no effect per say on traditional vapor clouds as the salt may actually introduce more CCN's but perhaps at the transition point from supercooled water to ice there would be some sort of negative effect on the micro physics of the cloud, e.g abnormal ice crystal growth? Especially if there is snow (or a snow growth region) falling through a zone of supercooled vapor that is between -1 and -18 C in temperature and the liquid saline content is above 50 ppm.

So, who knows what would happen?

Thanks!

 

[Jim Rood]

Tom,
Try Ambien...works wonders on that sleep problem.

 

[Shane Adams]

Tom,
Try Ambien...works wonders on that sleep problem.

What does it do for personality problems?

 

[Laura Duchesne]

Interesting thought, Tom. Wouldn't the precip just have higher contents of salt in it? Probably wouldn't be that good for vegetation, I suppose. Or perhaps any hail wouldn't form properly, since salt melts ice?

 

[JIM SELLARS]

Salt water rain and lots of lightning...

 

[David Wolfson]

I think it's worth exploring the initial premise to get an idea what you're dealing with. First, the pressure drop itself can only lift a column of water a few feet; so the transport mechanism is limited to spray atomization and evaporation of droplets to dry CCNs and lifting up into the mid-level precip forming zone.

I'm not an expert in ocean/atmospheric interface physics, but I think the amount of droplets and vapor produced is a function (linear, probably) of the water area acted on, and a function (power 2 polynomial, probably) of wave height and wind speed at the water-air boundary.

Just doing a thought simulation, I think the magnitude of salt water finding its way up into the cloud from the limited circulation of a tornado should be rather small. And it should be noted that dust, especially agricultural dust rich in nitrate fines, provides just about the best source of CCNs around. Many a lively supercell with or without tornado is a huge vacuum cleaner ingesting huge gobs of dust from miles around.

FWIW, my thinking is that the effect of salt water atomization would be negligible to very minor AFA preciptation formation is concerned. Salt spray affects vegetation, of course, but that comes aplenty from regular wave action in a stiff wind near salt water anyway.

 

[Aaron Kennedy]

I imagine it would have no effect per say on traditional vapor clouds as the salt may actually introduce more CCN's

Actually, CCN concentrations are higher over land areas due to dust and land-born aerosols. If you look at drop size distributions, marine regions typically produce rain that has a narrower distribution and with larger droplet diameters (fewer cloud/rain droplets due to less CCN).

Salt and other aerosols are actually extremely important for cloud microphysics. Without these aerosols, water wouldn't condensate until really large super saturations. Instead, the water/salt mixture allows the saturation vapor pressure to be lower than for pure water.

but perhaps at the transition point from supercooled water to ice there would be some sort of negative effect on the micro physics of the cloud

Cloud ice nuclei are pretty rare. When the exist, however, the Bergeron process occurs. Because the equilibrium vapor pressure is lower over ice than water, the ice crystals actually grow at the expense of water droplets. Water evaporates off water drops (leaving the salt) and deposits onto the ice.

 

[Aaron Kennedy]

salt water finding its way up into the cloud

Ok... a bit of clarification.

Seawater is composed of water with dissolved salts.

Cloud water will condense around typically an individual salt particle. The "salinity" of fresh water (cloud water) will be much smaller than seawater. There isn't "salt water" rain.

FYI and off topic: Areas of the ocean with more precipitation will have a lower salinity.

 

[Dave Gallaher]

There isn't "salt water" rain.

I can't dispute this, but there was an occasion in the mid 1980s when we were driving toward the Florida panhandle on I-65 in south Alabama on a day when some tornadic waterspouts had come ashore. Rain began to fall and suddenly we could smell the ocean very strongly while still many miles away, so we assumed it was ingested seawater content in the rain that was falling. Would this just be a sensory experience, or would the salt content be a factorable figure in such a case?

 

[Aaron Kennedy]

Flow off the gulf perhaps? If you think about it, consider how remote islands can support a population. Where would fresh water come from?

 

[Tom Stefanac]

Actually, CCN concentrations are higher over land areas due to dust and land-born aerosols. If you look at drop size distributions, marine regions typically produce rain that has a narrower distribution and with larger droplet diameters (fewer cloud/rain droplets due to less CCN).

Salt and other aerosols are actually extremely important for cloud microphysics. Without these aerosols, water wouldn't condensate until really large super saturations. Instead, the water/salt mixture allows the saturation vapor pressure to be lower than for pure water.



Cloud ice nuclei are pretty rare. When the exist, however, the Bergeron process occurs. Because the equilibrium vapor pressure is lower over ice than water, the ice crystals actually grow at the expense of water droplets. Water evaporates off water drops (leaving the salt) and deposits onto the ice.

That would readily explain the supersaturation presented in various RUC2 real time soundings from across the SE Gulf shore areas. I noticed several throughout February with strong LLJ WAA instances, the Feb 16 KHQZ sounding is a good example . There were several soundings in which I noticed dew points nearly 2C above the profile temperature, and the most dramatic supersaturation was present in the 980 - 875 mb range.

As for the Bergeron process, my concern is not so much with the actual growth of ice nuclei as CCN's as it is with the SVP and entropic aspects related to the freezing-point-depression surrounding saline concentration and snow growth. Supposing the SVP is relatively high in a cool but not excessively cold snow growth region, (e.g -4C @ 750mb) I would imaging snow growth would not be possible. This may not appear significant in terms of precipitation, but I was thinking it may have some negative effect on latent heat processes as well as electrostatic distribution in a connectively charged cloud.

I think it's worth exploring the initial premise to get an idea what you're dealing with. First, the pressure drop itself can only lift a column of water a few feet; so the transport mechanism is limited to spray atomization and evaporation of droplets to dry CCNs and lifting up into the mid-level precip forming zone.

I'm not an expert in ocean/atmospheric interface physics, but I think the amount of droplets and vapor produced is a function (linear, probably) of the water area acted on, and a function (power 2 polynomial, probably) of wave height and wind speed at the water-air boundary.

Just doing a thought simulation, I think the magnitude of salt water finding its way up into the cloud from the limited circulation of a tornado should be rather small. And it should be noted that dust, especially agricultural dust rich in nitrate fines, provides just about the best source of CCNs around. Many a lively supercell with or without tornado is a huge vacuum cleaner ingesting huge gobs of dust from miles around.

There were a number of instances where I have observed severe supercellular convection over the Gulf, one instances comes to mind from last spring. I recall seeing a strong supercell about 210 miles south of New Orleans complete with a hook echo and 100% POSH 3.5 inch hail returns, funny thing too is that there was a SHIPS report nearby (maybe 2 miles from the hook?) with 50G70 knot winds out of the SSW with an ocean spray comment. When I took a closer look this was clearly inflow into the storm because the buoy obs around the storm (100 - 300 mile range) had winds all in the 25 - 30 knot range and the wind direction was ESE. This largely agreed with the meso-analysis findings which progged the strongest sfc winds 25 miles ahead of the cold front at 30G35.

I have no idea and no way of knowing how much if any salt was ingested but this is the case which started me thinking me thinking. You know, one of those event that's make something in your brain turn haha.