FlyerTalker688786

Question

is the light above 30000 feet really 'natural light'?

and at what level the sun beam is still considered as 'natural light' for humans?

LondonElite

Dave Noble

That is completely flawed - you have no evidence to support your suggestion of a health risk

Do you have any hard evidence that it does - it is very hard to prove that something doesn't happen in all cases - and no good reason to when it would be logical to try and find the 1 case where it does

If you happen to sit adjacent to the window , you will be in a position to meet your health desires

jordyn

No one is shooting the messenger, but lots of people are telling you you have no idea what you're talking about.

Yes, radiation at altitude is a real thing. No, the window shades do not block it to any meaningful degree. If they did, some of your articles would probably propose that as a solution to the problem, don't you think?

jordyn

<Weird dup--deleted>

gmt4

Arguing about cosmic rays microwaving your innards or diminishing your ability to have children serves little utility. Rather, the point is far simpler that that: respect for your fellow passengers. This is why airlines ask to lower the shades. It makes for a more relaxing environment. Don't assume everyone is on the same sleep cycle as you, has the same rest/work habits, or wishes to have bright sunlight blasted at them as you operate "your" window shade. Its really pretty simple. Everyone who is a veteran flyer should know this, and if they don't understand it then they have no right to gripe about anything else. End of story.

LondonElite

It's really pretty simple. Daytime means it's bright, nighttime means it's dark. All living organisms should know this.

jordyn

Pretty funny to have someone argue that you should respect other people's opinions and then pronounce your own opinion on the window shade topic to be the definitive "end of story".

ashill

This is the second time you've used that line, and it's as bogus now as it was before. No one is shooting the messenger; we're pointing out that the message displays a lack of understanding of physics. (Mind you, that's not uncommon.)

This is where there's a slightly-subtle way in which your physics is wrong. It's only partly the radiation level that's a concern. If the radiation level is low enough so that you don't need a bunker to stop it, it's low enough so you don't have to worry about it. The intensity of radiation probably won't change measurably depending on whether your windowshade is up or down.

[wonkery]What matters is the energy level of the individual photon. A gamma ray is a photon with an energy of several thousand electronvolts or more. That energy means it can penetrate a long way through matter and do harm, hence the need for cement bunkers to protect you from gamma rays. A gamma ray will penetrate just as far on average whether there's one of them or hundreds of them. Therefore, the airplane window and metal (or carbon fiber, perhaps to a lesser extent -- I don't know) has a certain (low) probability of blocking a gamma ray; the windowshade also has a certain (but much lower because there's less mass) probability of blocking a gamma ray.

Here you're confusing "sunbeam" and "radiation". When we talk about sunbeams, we're referring to visible and ultraviolet light from the sun. Like gamma rays, those are electromagnetic radiation, but each photon has much less energy; the term "radiation" in common parlance refers to the high-energy photons as well as alpha and beta radiation, which are particles with mass, not electromagnetic radiation. Individual UVA photons have energies of about 3.5 electronvolts (ie about a thousand times less energy than a gamma ray); red photons have energies of about 2 electronvolts. Because they have so much less energy, it doesn't matter how many UVA photons you have: none will get through either a block of cement or a windowshade, whereas one gamma ray might get through a block of cement and almost certainly will get through a windowshade. Neither visible nor UVA photons can penetrate far into your skin. UVA photons can penetrate far enough to cause a sunburn and do some damage that over the long term can accumulate to lead to skin cancer. Red photons don't have enough energy to do even that: no amount of red light can ever give you a sunburn or lead to skin cancer.

There are subtleties related to atomic and molecular physics that determine whether intermediate wavelengths like UVB (≈4 electronvolts) and X-rays (hundreds to a few thousand electronvolts) get through windows, the ozone layer, glass, or windowshades, but I'll skip that except to say that windows block most UV, which is why you can't get a sunburn in a car unless the windows (or roof!) are down.

[/wonkery]

ashill

That is certainly true: there are legitimate arguments for keeping the windowshades closed, but radiation risk is not one of them.

On some flights, I hear you. For example, a midsummer flight departing the west coast of the US at 1 AM, flying north into the midnight sun, and then flying back south to land in Asia at dawn is a time when the best way to combat jetlag is to be asleep and make sure your body thinks it's night time. Open windows will let the midnight sun flood into the cabin and ruin that.

But for daytime JFK-LHR, the nominal topic of this thread, it's quite the opposite. The flight lands at around 22:20 UK time, which is 17:20 NYC time. For jetlag, you absolutely want to be awake and have your body think it's daytime until landing. A reading light doesn't tell your body that it's daytime: the best way to do that is daylight. The best way to get daylight on an airplane is to have the windows open. So closing the windows on a daytime flight is quite disrespectful to those who want to get on UK time and minimize jetlag, if one wants to play the "disrespect" card.

bobnchi

I'm impotent.......DYKWIA!!

On LAX/SYD recently, 787, they locked down the window control. It was a shame really as the sunrise was magnificent and having the camera in hand, I missed some good shots.

nrr

On a few n/s JFK-NRT (all daylight) the plane passed over Alaska, SUPER scenery.

Uncle Nonny

Agreed. I flew over Mongolia last week for the first time. As someone who grew up studying paper maps and atlases as a hobby, I thoroughly enjoy looking out the window.

gmt4

Your obsession with cosmic rays is curious at best and the argumentative approach isn't dignified. Obviously the point of my post escaped you, so I'm not going to carry this discussion further.

enviroian