I grew up in Ohio and live in Oregon now. The storms here are wimpy. I still miss the storms of the midwest.

Only to some degree, though. I don't miss the tornado warnings and pitch black sky.

Interestingly, while those discharges are powerful, they don't really release energy in a form that a thunderstorm can actually use. The amount of energy being released just by condensation alone dwarfs the electrical output of a thunderstorm by a large margin. I think of the electrical discharges as just a byproduct of the storm, in much the same way as exhaust is the byproduct of the mechanism that makes a car move.

If I'm wrong, I'd most certainly like to know, because the mechanisms by which that kind of electrical current could kickstart a mesocyclone or tornado would be fascinating.

My guess would be that for the most part ground friction really doesn't affect the growth of a tornado, or even the trajectory. I think what it *would* do is affect the intensity and damage of wind over the bottom 25 feet or so. I'd be interested in seeing what happens, though, when a tornado occurs over a cliff or a large hill.

I'm guessing they'll continue to run simulations and five years later we'll learn something else interesting and groundbreaking.

Yes, it is quite fascinating. I started learning this stuff because as a child I was afraid of thunderstorms. Learning how they worked made them far more interesting than scary, though a loud thunderclap in the middle of the night can still freak me out.

There is nothing like being underneath a supercell as it approaches, and the sirens are going off, and the lightning is crashing all around you. The fact that it's nothing but a giant cloud does nothing to dampen the experience.

Learning how thunderstorms work is something I think everyone should do on a basic level - they are utterly fascinating. What is amazing to me is that these repeatable and frankly amazing structures are created out of nothing but air, water, and heat in varying combinations.

In layman's terms (and while I'm a layman I'm educated enough to be able to say that) a thunderstorm is simply caused by buoyant air rising. As it rises, the moisture inside of the air condenses, creating a cloud and releasing heat (latent heat). That warms the "parcel" of air more (another term he used frequently) and it rises faster.

Air that rises sucks up more air from below it because it creates a low pressure region. Eventually the air hits the top of the troposphere, which is stable (stable means that the air is warmer than the rising parcel and the rising air is no longer buoyant. Keep in mind that "warmer" is relative and can mean -60F.)

In conditions that cause a storm like this to form, vertical wind shear is important. In a pulse thunderstorm, the downdraft (the rain cooled air) gets in the way of the updraft and chokes it off. But the wind shear not only causes the updraft to rotate, it pushes the downdraft out of the way of the updraft, so nothing chokes it off. This is why when you look at a supercell, it is nearly always tilted to the direction of travel. (mesocyclone is another word for updraft in this case.)

Now that the storm is created, you have room for the other factors he was mentioning, such as the RFD, FFD, etc. Basically there is a certain combination of factors required to set the air at the ground to spinning. The interesting thing about this simulation was that the managed to find the sweet spot and get their simulation to create a long-tracked tornado. Much of his presentation was spent highlighting certain parcels of air and showing how they got ingested by either the meso or the tornadic circulation (which are related but not necessarily the same thing.)

Thank you. Not bad for a sysadmin. :) I've always had an interest in how storms work, though it's not nearly as involved as yours, obviously.

I think there's a difference between showing how a tornado works when it's already on the ground (with which you could make models that accurately represent the tornado itself - the "most critical" parts of the storm) and how a tornado forms and is maintained by the larger structure of the storm. For the latter, you need a model of the scale that you created.

I actually watched your video twice and might watch it a third time. It's so informationally dense that there are details I missed the first time around. That anticyclonic circulation to the south of the tornado itself was observed with the latter El Reno tornado, and it's cool to see where it comes from.

Not Orp, but I would guess that this isn't possible because the entire storm acts as a system. Not only that, but the environment around it as well. That's why the box he was using was 120kmx120x20.

First of all, you have the updraft and the downdraft interacting with each other - and these two parts are actually the critical parts of a storm - and they're the *whole* storm. But the storm wouldn't be powerful without external factors influencing and driving it. A high CAPE (convective available potential energy) and thus a strong lapse rate, strong vertical wind shear (which helps to induce rotation and tip the downdraft out of the updraft's way), an RFD (which doesn't really specifically come from the storm itself), inflow, etc. These are all factors that feed and "nourish" the storm.

Trying to make a model that only focuses on the critical parts of a storm would be like trying to make a model of a car that only focused on one piston.

Somehow I don't think the scientists bothered to add trailer parks to their simulation.

Oddly, the question at the end *did* sort of cover that question, as trailer parks would count as ground friction.

There was a lot of jargon. Let's see if I can help.

baroclinic == energy created by movement of air because of differences in pressure.
forward flank downdraft == I believe the downdraft caused by the air cooled by the rain, also could be air forced down by the forward movement of the storm. Usually cool and wet.
rear flank downdraft == warm, dry air that hits the storm from the back and is forced downward.
mesocyclone == the rotating updraft in a supercell.

Basically, he's stating that the interface between the different types of air on the ground is creating a rolling tube of air, and the updraft of the storm is so powerful that it sucks that tube up - and the energy of the rotation helps to give the updraft an extra "kick"... which helps to power and maintain the rotation of a long-track tornado. That tube isn't the tornado itself, it just powers the updraft that spins the tornado.

This is pretty amazing. I've heard the theory before that tornadoes are formed from that same baroclinic horizontal vortex tilting upwards, but the mechanism for that has never made a whole lot of sense to me. The idea of it getting pulled up into the actual mesocyclone itself and powering it so that the tornado can form makes a lot more sense. It also makes it a lot more clear what role the RFD has in tornadogenesis. And that parade of vortices, I'd never heard of that before.

Hopefully this will help the weather people start to see clues that a tornado is trying to form even before the hook starts to become obvious on radar.

In Oregon, it's "Stop if you can". You are to treat the yellow light as a red light unless it is unsafe to stop.

And this would not be an issue if he wasn't an arrogant person who treats systemd like his own personal playground.

Back to my point. His Google+ nick says everything that needs to be said about his management style.

No real need to assassinate that which is already dead.

I'm sure he's a just fine person, who has no intention of ever listening to anyone who might know a better way.

Just as an aside, have you noticed that his Google+ username is LennartPoetteringTheOneAndOnly?

This says pretty much everything that needs to be said regarding his mindset. To your point.

That's one FS I think the linux world could, at the moment, do without. It's got some cool features, but is not ready for primetime.