Saturday, July 28, 2012 6:22:41 PM
Mammatus clouds are NOT something you wanna have hanging over you; they're the precursor to violent thunderstorms (by violent I mean USA level violent) - Asian level applies in many things, but the USA tops the bill in the thunderstorm stakes. Best case is a medium level thunderstorm. Worstcase is a supercell with multiple tornadoes. It`s one of those "I hope it goes some place else" things.
The good news is that it`s exceptionally rare for Europe (where I live) to get such clouds.
That said, Cumulonimbus cloud is also not great if it`s heading for you, it too can generate severe weather, i.e. violent thunderstorms, potentially. That said, given a choice, I`d take cumuloniumbus every single time. There`s less of a severity factor. We get them regularly in the summer in Europe; I saw several today in fact. One of them decided to rain on me even. I was not impressed. I got soaked. Bastard cloud.
Saturday, July 28, 2012 11:11:54 AM
If you're truly curious, look up Kelvin-Helmholtz instability, Plateau-Rayleigh instability, Rayleigh-Taylor instability, von Karman streets, and Taylor-Couette flow.
Those pretty much explain most of them, most are instabilities in an otherwise sheet-like flow due to a number of factors, most important of which is the difference in speed of two non-miscible fluids (it also explains how sea waves are made from the difference in speed from water and air).
You can see my experiments here along with some other cool fluid stuff.
That`s how they work. WHY they happen after/during/before some specific natural phenomenae... I don`t know.