How to Spot a Psychopath

A reader writes:

I was flying at night from Chicago, IL to Cleveland, OH. It was a very cool but humid night. Since this was a short flight (1:10) we were in a fairly low altitude commuter jet. There are a lot of small towns between the cities separated by nothing much. It was a clear night and we were of course well above the sparse clouds. They were sparse, that is, until we flew over a town; a short way into the town a low overcast began.

Looking down on it, you could see the street and street lights as you began to cross the town, and the thickening, low-lying overcast, enough to obscure everything, until you reached the town edge, after which it thinned out and disappeared shortly before you reached the actual edge of the town, if you see what I mean. If the town was a disc, the overcast would be a somewhat smaller diameter disc centered and overlaying it.

We also flew over several football fields with their field lights on. By the lights, there was a cloud. Away from them, say by the middle of the field, the cloud stopped.

It was weird and after making this hop more times than I can count I've never seen it before. I'm sure it was a function of the cool temperatures (low 40s), high humidity and the local warming from the lights and from the cities themselves. But I can't think of a mechanism.

Mike

Clouds often form over towns, as a side-effect of the urban heat island effect.

Towns are usually warmer than the surrounding countryside, because we make our towns out of substances like brick and asphalt, which absorb and retain solar heat better than grass and trees. Because the towns are warmer, the air above them tends to be warmer and thus less dense than the air around the town. So the air over the town rises, and air around the town is sucked in to replace it, whereupon that air warms up and rises too. It's sort of like the fire-bombing of Dresden except, you know, less horrifying.

(The urban heat island effect is a favourite of climate-change deniers, who allege that rising temperature readings over the years are explained by those readings being taken in places which genuinely are getting hotter, but only because they contain more and more buildings and roads. These higher temperatures do not, the argument goes, therefore indicate any actual overall climate change. The claim that the world's climatologists wouldn't have noticed and compensated for this phenomenon is, to my mind, about as plausible as the creationist allegation that paleontologists don't know that carbon dating doesn't work on things that are millions of years old.)

The warm air rising over a town will cool down as it rises and mixes with the rest of the atmosphere, and the cooler air is, the less water vapour it can hold. If the air over the town was humid - which it often is over Chicago and Cleveland, since they're each on the shore of a huge lake - then clouds will form as the rising air cools and water condenses out.

I think the particularly striking effect you saw was the result of the local weather being just right to give a textbook demonstration of the heat-island-clouds effect, even around small heat sources like floodlights.

Pollution from towns may also encourage cloud formation, because soot and other particulates can serve as nuclei for atmospheric water vapour to condense onto. This phenomenon is used in agriculture to prevent the formation of frost; oil-fired "smudge pots" burning with a nice dirty smoky flame don't actually greatly warm the orchards they're sitting in, but they do produce lots of nice little particles for water to condense onto, and then drift away. This reduces the amount of water that condenses on the trees and, later, freezes.

Making clouds in this way is quite easy; making rain in some particular place is a lot harder.

(Note, by the way, that clouds are not made of water vapour. Water vapour is a gas, and invisible. The clouds you see in the sky, and the visible "steam" from your kettle, are tiny particles of liquid water. This also means that visible "steam" at normal atmospheric pressure can't be any hotter than 100°C. True, invisible, steam can be much, much hotter than this. You can get a nasty burn from the visible "steam" that appears some distance from, say, an open stopcock on the side of an old locomotive, especially if you're close enough to the nozzle that there's still some actual vapour in there. But the invisible "live steam" closer to the nozzle can, quite literally, flay the flesh from your bones.)

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

Here's an interesting science question (for me at least!).

I've often observed a phenomenon. In sunlight - especially early or late when the sun is low and the rays come low - you can play with shadows on fairly distant objects (few meters); this seems essential for the effect.

The effect itself: If you move your fingers close to each other, while the sun shines through between them, as you close the gap between the fingers, the shadow of your fingers seem to stretch out and touch well before they actually touch. (Of course you don't have to use fingers, you can use something else.)

It's weird, really weird.

Steve

The sun isn't a point source of light; like most light sources, it has a clearly visible diameter. All shadows from it are, therefore, fuzzy to a greater or lesser extent, depending on how close the shadow-casting object is to the surface on which the shadow is cast.

A fuzzy shadow has an "umbra" and a "penumbra". The umbra is the evenly-dark portion of the shadow; if you're standing in the umbra, you can't see the light-source at all. The penumbra is the portion around the umbra which is partially shadowed. If you're standing in the penumbra, you can see some, but not all, of the light source's area. The closer you are to the umbra, the less of the light source you can see.

The umbra and penumbra distinction is particularly important if you're trying to get a good view of a solar eclipse; in a partial solar eclipse, the moon never covers the whole disc of the sun. You can see this in that famous picture of a solar-eclipse shadow viewed from low earth orbit, and it's diagrammed, rather less beautifully, here:

(Note also the "antumbra", which you see if you're far enough from the shadow-casting object that you see the light source all around it. This illustration's good, too. In a lunar eclipse, the moon is covered by the earth's shadow; a lunar eclipse is partial if the moon is never completely covered by the umbra of the earth-shadow.)

Now let's get back to the shadows of your fingers when you're doing Deformed Rabbit in late-afternoon sunshine. The shadow of each of your fingers, when it's cast by a light with considerable angular size like the sun or a much closer, much smaller light source like a light bulb, also has an umbra and a penumbra. Where two finger-shadow penumbrae overlap, an ant squinting up from the overlap area would see one side of the sun obscured by one of your fingers, and the other by another finger.

Result, a darker shadow, as the penumbrae add up. As you've noticed, this makes it look as if the shadows are stretching toward each other.

(You don't see this effect very much with most household lighting, because most people don't paint their rooms matte black and light them with a single dangling frosted bulb. Uneven illumination escaping from a lampshade, and indirect light bouncing off the ceiling, make normal indoor lighting quite unlike sunlight on a clear day, even if there's only one light source in the room.)

Freaky shadows can also be caused by diffraction effects, but with a wide light source and relatively large shadowing objects, you won't see them. If you've got a really really tiny light source with, preferably, a very tightly limited spectral output, though, all shadows will be super-sharp (with invisibly small penumbrae), and diffraction effects spring into visibility.

You can get such a light source if you unscrew the collimating lens completely from a laser diode module; this is possible with many, but not all, cheap laser pointers. Now you've got a narrow-spectrum light source about the size of a bacterium to play with!

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

You can get high on nutmeg. You really definitely can, it's not like smoking banana peels or gum leaves or something.

So why isn't nutmeg illegal?

F.

Yes, nutmeg is indeed a psychoactive drug. You need to eat a fair bit of the stuff, especially if it's not fresh, but it'll make the world look different all right.

Unfortunately for the hopeful supermarket trip-taker, though, being high on nutmeg is a rather unpleasant experience. The main active ingredient is "myristicin", which in the nutmeg plant serves to keep insects from eating it.

Like a number of other psychoactive compounds present in plants you can legally grow, myristicin is a "deliriant". It can cause pleasant effects - euphoria, interesting dreams while you're still awake - but it can also just stupefy and confuse the user, essentially giving you a preview of severe senile dementia. Effects of large doses of myristicin include headache, body pains, anxiety and vomiting, though usually not death. In this last respect myristicin is superior to the psychoactive compounds in other "legal" plants, like Echium plantagineum ("Paterson's Curse") and Datura stramonium ("jimson weed").

Myristicin also takes some hours to take effect, and can then last for a straight day before it even starts to wear off. The first quality results in overdoses, when after five hours of nothing much happening the user decides to knock back another bottle of nutmeg. The second can lock the user into a very lengthy tour of a place you'd much rather not be.

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

My brilliant son put a jar of mustard in the microwave for... a while. When we regained the ability to breathe and I managed to stop laughing, I grounded him because of his clear violation of the Chemical Weapons Convention, to which Australia is a signatory.

Then I started thinking. We just inhaled gaseous hot English mustard... does that mean we just inhaled mustard gas? Are we now at a higher risk of lung cancer, or something?

Caitlin

"Mustard", in culinary parlance, is a condiment made from mustard-plant seeds. Hot mustard is bad news if you get it in your eyes or sinuses, on account of a compound called allyl isothiocyanate, or AITC to its friends.

"Mustard", in chemical-weapons parlance, refers to any agent which creates a burning sensation and "lachrymatory" effect similar to that of AITC, and generally also has a somewhat similar smell to culinary mustard. These compounds are not at all related to edible mustard, though, and all have exciting extra toxic effects. The original "sulfur mustard" compounds that were used in World War I, for instance, are highly carcinogenic and cause agonising skin blisters and chemical burns, which can take as much as a day to develop.

It would be unwise of me to mention, in these pages which your son may read, that microwaving pepper can create a similar noxious cloud, the active agent in which is "piperine".

So I will not.

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

Why can't you see the bones in your finger/hand when you shine a bright light through it? Veins show up well, but bones are practically invisible. Are live bones as see-through as live flesh?

Ryan

Bones, alive or dead, are pretty much opaque to visible light. If your flesh were for some reason perfectly transparent but your bones stayed as they are, you'd be a lovely Ray Harryhausen walking skeleton. (Or, more accurately, a Fritz Leiber ghoul.)

Your flesh isn't transparent, though; it's translucent, and diffuses light that enters it. So instead of your hand-bones being as visible as a fish in an aquarium, they're as invisible as a fish that is for some reason attempting to survive in a tank full of milk.

If that fish in its milk-tank comes close to the side of the tank, you'll be able to see it, just as you can see the little dark veins that're close to the surface on the palm side of your fingers when you shine a flashlight through your hand. Just the few millimetres of flesh on either side of the bones, though, diffuses the light so much that it's hard to tell that there's a bone there at all.

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

Most cigarettes have a wrapping around the filter that looks like cork, because apparently the earliest filter cigs had a filter made of cork.

How the hell did that work, though?

Isn't cork used for, well, corks, because it's impermeable? How could you suck smoke through a cork? Perhaps smokers in 1940 were more health-conscious than we thought, and enjoyed these Unsmokable Health Cigarettes!

Luca

Today, most cigarette filters are made of cellulose acetate fibre, a substance of many uses (from cloth for garments to stuffing cushions) which is made by reacting plant cellulose with acetic acid.

But cigarette filters are, as you say, usually covered with a layer of paper printed with a cork pattern. And yes, that's because in the olden days the filters were made of cork. (This makes the printed-paper filter a "skeuomorph", an object with cosmetic design elements held over from an older version of the same thing.)

Cigarette filters were, however, never solid cork; as you say, that would be ridiculous. Instead, the filter was actually filled with loosely-packed cork granules, or a loosely-rolled piece of paper, which might itself have been made from cork.

There's nothing about cork that makes it a particularly excellent filter material. It was just a relatively cheap substance that wouldn't do anything very alarming if the smoker smoked all of the tobacco and sucked the flame back into the filter.

Cigarette filters have the peculiar task of blocking some bad stuff from getting into the smoker's lungs, without blocking the bad stuff that the smoker's paying to put into their lungs. (See also guns, which are generally designed to be simultaneously as safe, and as dangerous, as possible.)

So a really good filter material, like activated carbon, would be no use in a cigarette. Instead, filter materials with relatively low surface area are used. Activated carbon works so well as a purifying filter because it's immensely porous, giving it an enormous surface area per gram and allowing it to "adsorb" a surprising amount of stuff. Cellulose acetate fibres, of a similar consistency to cotton wool, adsorb rather more "tar" than the old cork filters, while letting various other compounds through.

Both cigarette filters and long cigarette holders do catch some particulate matter and "tar", but their actual effect on smokers' health is difficult to detect.

(See also "light" cigarettes that have air holes in the paper around the filter to dilute the smoke. In theory, they could actually be somewhat healthier than regular cigarettes, but in reality, there's no good evidence that "light" cigarettes are any better. Smokers cover the holes with their fingers, or just smoke more, or more deeply; however it happens, health outcomes are the same no matter what mainstream-Western-market cigarette you smoke.)

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

A reader writes:

I was walking down the street at three in the morning after a night out, in the middle of winter [here in Australia], and there was twinkling frost all over the top of a parked car. And the next parked car. But not the one after that.

I kept looking, and the difference was that cars that were parked under a tree had no frost, but cars that were in the open were frosty.

The air temperature was pretty low, but it wasn't below freezing - I checked later and the local weather station said it got down to about 4 degrees C.

Did frost fall down out of the sky and somehow... stay?

Finn

It was a clear night with no breeze, right?

On a clear night, the sky above you is a window to deep space. There's no sun keeping things warm, no diffuse sky radiation making the sky blue and at least a bit warm wherever you look; just a blanket of air, and then space.

Heat can pass by convection, conduction and radiation. Radiation, for most items humans encounter, is the least important of these three paths. But if an object has a wide view of something which, like deep space, is close to absolute zero, then it can radiate enough heat to drop below zero Celsius, even if the ambient air temperature is a little above freezing.

If there's even a light breeze, the passing above-freezing air will keep surfaces too warm for frost to form, by allowing heat to move by convection - in this case forced convection (as in the case of a computer CPU's heat sink cooled by a fan). Likewise if a surface is directly connected to something with a large heat capacity, allowing that surface to stay warm by conduction (as in the case of the CPU itself, in physical contact with its heat sink). The thin steel roof of a car will form frost in these conditions; a solid block of steel would not, because radiation wouldn't be able to cool all of it enough before the sun came back up.

The less of a direct view a surface has of the sky, the smaller this already-small effect will be. So cars - or rubbish bins, or other thermally-isolated surfaces - that're in the "shade" of a tree or building probably won't frost up. (There could be some interesting odd cases, if for example a car is parked next to a skysraper covered with IR-reflective glass.)

This same phenomenon can be used to make ice in a desert, if that desert has clear, still nights. Wide shallow trays of water held up off the sand by narrow supports can freeze surprisingly quickly.

Psycho Science, as I have brilliantly decided to call it, is a new regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.