Why the sky is blue?

[00:00:04] chut with mini new so here's a question

[00:00:06] that strikes a chord with me, I'll add [00:00:11] razor-sharp acumen why is the sky blue

[00:00:17] that hasn't been answered since

[00:00:19] childhood you know what here's the

[00:00:21] problem I asked once and they were like

[00:00:24] Maya business and that was we might say

[00:00:28] I want to become an atmospheric

[00:00:29] scientist it is my business

[00:00:31] there you go that would have it a very

[Laughter] [00:00:33] [00:00:40] spirit scientist so alright so if the

[00:00:45] answer is easy to understand it's just

[00:00:48] not simple first of all is the sky blue

[00:00:51] yes okay well at least we got that it

[00:00:54] doesn't look blue to you it's fine

[00:00:56] that's what we're about to talk about

[00:00:57] all right okay so here's a deal the

[00:01:01] explanation is actually simple it just

[00:01:03] takes a little while to explain okay

[00:01:05] that's all alright alright I have time

[00:01:12] alright so we have an atmosphere okay we

[00:01:17] We did it, as everyone is aware. [00:01:18] it's composed primarily of nitrogen okay

[00:01:22] a 78% nitrogen that's 20 21% oxygen and

[00:01:26] a few percent other carbon dioxide this

[00:01:29] sort of thing mixed in there are

[00:01:31] pollen-like and dust-like particles and Sand from sandstorms and pollution and [00:01:34] [00:01:38] smog and so particulates particulates

[00:01:41] particulates okay now light comes from

[00:01:45] the Sun mm-hmm

[00:01:47] white light people people say the Sun is

[00:01:51] yellow it's white right okay exactly

[00:01:53] you've seen the Sun in the middle of the

[00:01:54] Day is white, which explains why that's the [00:01:57] proper color of the Sun in the middle of

[00:01:59] Today, let's not accept racism. [00:02:02] must be the appropriate cup, so why is [00:02:09] everything Rachel into you

[00:02:16] all right so you may remember that white

[00:02:20] light is composed of colors right okay

[00:02:22] put this light prism that's how you get

[00:02:24] a rainbow right or your your educator

[00:02:26] you said prison but through a raindrop

[00:02:28] it spreads mounted to college and you

[00:02:30] Obtain the rainbow's colors. [00:02:31] Give me the Boise bibs, right red. [00:02:33] Roy igb Roy red orange green blue yellow [00:02:39] green Roy yeah red orange yellow green

[00:02:43] blue and ultraviolet but Valley bid okay

[00:02:49] indigo violet thank you red red orange

[00:02:52] yellow green blue indigo okay the seven

[00:02:56] the spectrum's colors are in order. [00:02:57] if you come the way our brain works and

[00:03:00] the sensors in your retina okay the rods

[00:03:04] the cones the other rods give you shades

[00:03:06] of light and intensity the cones a

[00:03:10] disentangle color okay okay and you have

[00:03:15] an RGB cones this week at RGB for I

[00:03:18] heard that in computers and computer

[00:03:21] screens and everything okay so you're

[00:03:24] You are chemically associated with the [00:03:27] chemicals in your retina splitting that

[00:03:29] red light into red-green combinations [00:03:31] and blue okay okay broad combinations of

[00:03:34] these three if you have more red than

[00:03:36] The others are superior to what you see: [00:03:38] will appear redder to you if you [00:03:39] have more blue than the others gonna

[00:03:41] look blue now here's what happens white

[00:03:43] sunlight falls from the Sun. [00:03:52] particles in the atmosphere some of them

[00:03:56] are about the same size as the

[00:03:58] the wavelength of blue light, fine. [00:04:02] now if the if you have a particle and

[00:04:04] light and a particle are identical. [00:04:06] If you size that correctly, it will show that's [00:04:08] Yes, it will either scatter, which is the [00:04:10] acceptable word, bounce, scatter, and so on That light doesn't make it straight [00:04:13]. [00:04:15] through its sins in every other

direction [00:04:16] [00:04:17] oh so the light from the Sun is

[00:04:22] has the blue selectively. [00:04:24] moved toward the surface of the Earth. [00:04:26] The blue then disperses into the [00:04:29] air and you have a blue sky that's very

[00:04:32] romantic is beautiful now

[00:04:34] it's called Rayleigh scattering got him

[00:04:37] Rayleigh greatly we get it re yl aigh

[00:04:40] okay Lord Rayleigh you and Lord the Ray

[00:04:47] alright so so here's the thing as the

[00:04:51] Sun gets lower in the atmosphere right

[00:04:54] the path length of the light is much

[00:04:57] longer through the air okay so in other

[00:05:00] words so here's your atmosphere if

[00:05:02] you're directly above you're going

through it with this thickness and [00:05:03] [00:05:05] should come down the thickness gets more

[00:05:07] All right, fine, good, more atmosphere [00:05:09] more scattering right the sky gets more

[00:05:13] blue okay so in the daytime it's quote

[00:05:16] sky blue that's actually a pale Braille

[00:05:18] it's a very pale as you go to Twilight

[00:05:19] that sucker gets deep yeah it gives deep

[00:05:22] blue and so much more blue gets taken

[00:05:26] out of the Sun I just love how violent

[00:05:28] deep blue it's deep and if you take that

[00:05:31] much blue the Sun I got no blue light

[00:05:34] left, so what color will it be? [00:05:36] turn kind of red kind of red gotta read

[00:05:40] got a red amber yeah okay that's why

[00:05:42] sunsets are red that's because so much

[00:05:45] Blue was eliminated, so that's what's [00:05:48] The side is all it has left to offer. [00:05:50] of the spectrum we have red orange

[00:05:51] yellow that's know sometimes you have a

[00:05:54] very bright sunset that's not quite deep

[00:05:57] red mark many particles therefore that

[00:05:59] sunset all right many particles sweet so

[00:06:03] that definitely has a lighter cut, yes. [00:06:07] so so the sky wouldn't get as intensely

[00:06:09] blue when that happens it'll be similar

[00:06:11] to the sky blue you had earlier in the

[00:06:13] day so that's that's why we have a blue

[00:06:16] The sky is now nice, which is also why you can't see. other daytime stars than the Sun [00:06:20] [00:06:23] well it's not it's not oh you can't see

[00:06:26] stars they come because the Sun is out

[00:06:27] that's not why because the Sun is

[00:06:29] brighter than the star light that you

[00:06:31] would otherwise see

[00:06:32] no that's not why well see that's

[00:06:33] intuitive knows how you with intuitive

[00:06:35] but it's wrong

[00:06:37] the reason why you can't see stars in

[00:06:39] the daytime is because the scattered

[00:06:40] blue light has rendered our atmosphere

[00:06:43] aglow the answer is glowing blue light

[00:06:48] as a result, you can't see the [00:06:51] If you took away the stars behind it, [00:06:53] atmosphere you'd be able to look up and

[00:06:55] see the Sun will be there but then you

[00:06:57] like dark adjust over here and there's

[00:06:58] Fulton Scott full stars right over here

[00:07:01] over there over there all around oh man

[00:07:03] you know what what if we didn't need

[00:07:06] atmosphere I'd want to get rid of it

[00:07:07] okay so now this is what led to the

operational definition of the edge of [00:07:13] [00:07:16] The atmosphere is fine; it just is. [00:07:19] it's kind of operational it is how high

[00:07:22] up in the air do you have to go before

[00:07:24] there aren't so many air molecules above

[00:07:27] you for the blue light to scatter and

[00:07:29] prevent you from seeing the night sky so

[00:07:31] it's really about the number of

[00:07:33] particles it's not against an hour the

[00:07:36] actual no it's just a density particle

[00:07:38] wherever that happens so we agree just

[00:07:41] by convention if you go up a hundred

[00:07:43] kilometers okay converted to get 62

[00:07:45] miles hundred kilometers that's about

[00:07:47] where the atmosphere becomes less dense in this way [00:07:51] there's no longer scattering blue light

[00:07:52] it is no longer a glow and in broad

[00:07:55] daylight you can see stars in the

[00:07:56] nighttime sky so that's the operational

[00:07:59] definition of space the operational

[00:08:02] definition of space is 62 miles above

[00:08:04] our ground surface kirai surface where

[00:08:08] you can just see space basically because

[00:08:11] that Mikayla's is still a mystery there

[00:08:13] was not dense enough to scatter blue

[00:08:16] light and render it a glow to prevent

[00:08:17] you from seeing the night sky

[00:08:19] now I'm not comfortable with that opera

[00:08:21] I understand it okay I'm not comfortable

[00:08:23] now what's your problem with that

[00:08:24] because if the atmosphere were half is

[00:08:27] thick as it is whether that would be

[00:08:29] only be 30 31 31 miles that would be

[00:08:33] space well suppose we're a tenth is it

[00:08:36] then it would be three miles suppose we

[00:08:38] didn't have an atmosphere

[00:08:39] you'd be a space just standing here

[00:08:41] sitting here like this

[00:08:42] Should that be referred to as space? claiming that this is our definition of space is [00:08:45] [00:08:47] related to the way the circles work. [00:08:51] answers of our atmosphere that Cottam

[00:08:53] except well no I see what you're saying

[00:08:55] now because I was about to say it kind

[00:08:56] of makes sense because you can't breathe

[00:08:59] out there in space, but you can't breathe. [00:09:02] at 35,000 feet

[00:09:04] that's why yes where you can breathe

[00:09:28] hard enough to breathe just on a

[00:09:30] mountaintop exact you've won a quarter

[00:09:31] mile on a mountaintop so now you said

[00:09:38] what was your operational definition of

[00:09:40] space be if it is not indeed this this

[00:09:44] particular in atmospheric link I've

[00:09:48] thank you take out the atmosphere either

[00:09:49] you're in orbit or you're going

[00:09:50] somewhere then you're in space so you're

[00:09:52] using

[00:09:52] oh god you a