good question!! I actually might have been mistaken by saying sea salt was an INP (whoops).
Sea salt is a great condensation nuclei (CCN). CCN allow cloud droplets to form instead of ice crystals.
For cloud seeding to work well, it’s better to seed with INP instead of CCN because if you encourage lots of droplets to form, all you get is a bunch of really tiny droplets, making a really bright white cloud (no rain!). (Side note: that’s why rain clouds look dark: they’re made of fewer really big droplets.)
Adding sea salt to clouds is a thing though! It’s been proposed as Marine Cloud Brightening - adding lots of sea salt to the air over the ocean, making the earth more reflective to combat further global warming.
As far as I know, most inorganic salts are good INP or CCN, but have varying efficiencies. Sea salt dissolves in liquid water whereas silver iodide doesn’t, and silver iodide has the right sort of hexagonal crystal lattice for ice to start sticking to. So silver iodide is a great INP whereas sea salt is a great CCN.
Why use silver iodide instead of sea salt like what typically happens naturally? Silver iodide sounds expensive to manufacture compared to sea salt.
good question!! I actually might have been mistaken by saying sea salt was an INP (whoops).
Sea salt is a great condensation nuclei (CCN). CCN allow cloud droplets to form instead of ice crystals.
For cloud seeding to work well, it’s better to seed with INP instead of CCN because if you encourage lots of droplets to form, all you get is a bunch of really tiny droplets, making a really bright white cloud (no rain!). (Side note: that’s why rain clouds look dark: they’re made of fewer really big droplets.)
Adding sea salt to clouds is a thing though! It’s been proposed as Marine Cloud Brightening - adding lots of sea salt to the air over the ocean, making the earth more reflective to combat further global warming.
As far as I know, most inorganic salts are good INP or CCN, but have varying efficiencies. Sea salt dissolves in liquid water whereas silver iodide doesn’t, and silver iodide has the right sort of hexagonal crystal lattice for ice to start sticking to. So silver iodide is a great INP whereas sea salt is a great CCN.
Even longer (and reasonably silly) explanation here: https://www.acsh.org/news/2022/09/01/why-are-clouds-seeded-silver-does-it-work-16538