I was in Pahao a couple of days ago quite close to the Kilauea volcano. The plume from a large partial caldera collapse apparently came right over us. The rain that came down was falling at about 4 inches an hour according to my friend’s rain gauge. The strange thing was how localized it was. We called my friend’s wife in Hilo (only a few miles away) and she said it was sunny. After waiting about 2 hours for the rain to stop so we could continue to unload the container, we gave up. We only had to drive about two miles before we got out of the rain, but my friend said it continued to rain at his farm where the container was another 10 hours!
Was it the plume seeding the local clouds or just a 12 hour local “cloudburst”? Puna can easily get over 100 or even 150 inches of rain a year so I suppose it could have been just a regular storm. Can volcanic plumes seed clouds?
Not only do volcanic eruptions seed clouds, but they also tend to release a lot of water vapor, which further contributes to local cloud formation and local rain.
You also end up with frictional charging in the ash cloud, which can often create localized lightning in and around the eruption.
The volcanic ash would be a seeding source if the atmosphere didn’t already have enough, and that’s generally not the case … so maybe a little bit of that rain was extra because of the ash, however as e_c_g points out there’s also quite a bit of extra water vapor included in these ash clouds, and water vapor at a very high temperature … if we have saturated air at 300ºC and drop the temperature down to 50ºC, that water will condense* whether there’s nucleation sites or not … so I think that this is why you experienced this excessive rainfall in that specific location … and remember that cloud droplets themselves act as nucleation sites …
That said, this ash tends to remain suspended in the atmosphere for weeks, months and perhaps even years afterward … so the contribution of volcanic ash in cloud formation is an on-going thing and on a world-wide basis … so this one volcanic eruption adds to the load but we have to look at all the eruptions over the past few years collectively and here we will see more rainfall … along with just dust blown up into the air, pollen, salt and indeed meteor debris (ha ha ha, get it, meteorology) …
= or deposit, water vapor changing state directly to ice …
Didn’t I hear something about the bay getting filled in by lava? So it’w not a bay anymore but the opposite (no longer an “innie” but and “outie” now)?
However, the eruption is on the cooler and rainier side of the island. I was on the big island a couple years ago, staying on the west coast. We drove over to the park to have a look at the volcano, which wasn’t doing much, but it absolutely pissed down rain all day long. Driving back, it was like going through a curtain–cold and rainy one side, warm and sunny the other.
I’m not disputing that Kilauea is affecting the weather, but it may be exacerbating conditions that would exist anyway.
I believe mangroves could grow right away with their roots in the water, but I would think that organic material must pile up and rot to become soil. Fifty years? Hundreds of years?
When I visited the Big Island, I went to the site of a lava flow from around a decade earlier. It was pretty barren, but there were a few coconut palms and other plants growing in the lava field.
(I own a home in Hawaii and used to live in the Puna district on the Big Island)
Often the first life to form is lichen because it can live without soil. Ferns are next and can be seen growing in lava that is only a year or so old. Rainfall makes a huge difference and the Kilauea area gets over 80 inches on average. Another important factor is wind. Strong breezes blow in dust to the lava areas and airborne seeds germinate in these small pockets of soil.
Metrosideros polymorpha (or in Hawaiian “ʻōhiʻa lehua”) are the first real trees to grow in “fresh” lava. They are pretty much the only kind of tree you will see in the “recent” lava flow areas.
People who live in the Puna area try to find cracks or crevices in the lava on their property. They fill these areas with bags of soil and plant trees. The roots eventually break up the lava underneath and grow quite well.