Why can't we see air. "The Great Invisible - Air"

For parents:
Look at the poster carefully with your child.
It encodes the basic properties of air.

• air has no shape
• air has no color
• the air has no taste
• air is invisible
• the air is odorless.

To prove this, you have to go with your child

conduct a series of experiments.

Experience No. 1 "Air has no shape"

You will need:

• three balls of different shapes.

Target:

prove that air has no shape.

Experiment progress:

The child inflates three balloons of various shapes.

What's happening:

The air takes on the shape of the balloon you just inflated.

Conclusion: air has no form.

Experience number 2 "Air has no color"

You will need: paper .

Target: show that air is transparent.

Experiment progress: Compare air with opaque objects.

Let's take a sheet of paper. It is opaque - through it we do not see the surrounding objects. And you can see everything through the air.

Conclusion: so the air has no taste.

Experience No. 4 "Invisible Air"

You will need:

• two bowls of water and a glass.

And now you again offer to lower the glass into the water, but now hold the glass not straight, but slightly tilted.

What appears in the water? (bubbles). Where did they come from? (Air comes out of the glass and water takes its place) And why did we first think that the glass was empty? (Because air is not visible, it is transparent)

Experience number 5 "The air has no smell"

You will need:

Tasks:
* educational - to enrich and systematize children's knowledge about the air and its properties: transparent, colorless, odorless, tasteless, density, it is everywhere, mobility; with such natural phenomenon like the wind, the causes of its occurrence; with how a person uses the air (wind).
* developing - to develop interest in research activities; develop thinking and imagination; establish simple connections, draw conclusions; to teach, on the basis of the identified properties, to establish patterns.
* correctional - to support the child's desire to actively engage in communication, speak out; activate children's vocabulary.
* educational - to cultivate curiosity, interest in the world around us, the ability to work in a group.

Preliminary work:
Observations while walking for the wind, clouds.
Making paper fans with children.
Reading: S. Marshak "Ball", "Soap Bubbles",
Russian folk tale"Bubble, straw and bast shoes"

Vocabulary work:
Transparent, elastic, wind - the movement of air.
Benefits:
Cups of water and straws, fans for each child, plastic bag, balls, balloon, bubble, pipes, lionfish.
Lesson progress:
Educator: Today we will study the mysterious invisible substance. You cannot see it with your eyes and touch it with your hands, guess the riddle:
Invisible mischievous
Lives next to you
He is invisible and inaudible
And wherever we go
We'll find the invisible.
Children: Air.
Educator: Guys, let's try to get to know him. Where to look for it?
Children: He is everywhere: in the room, and in the ground, and in the water.
Teacher: Why can't we see him?
Children: The air is transparent, everything can be seen through it.
Educator: Do you want to see the air, feel it? How can it be detected if the air is invisible? Let's do some experiments. I invite you to our laboratory.

Experience 1. "There is air in the glass"
Turn the glass upside down and slowly lower it into the jar. To draw the children's attention to the fact that the glass must be held very evenly. What happens? Does water get into the glass? Why not?
Conclusion: there is air in the glass, it does not let water into it.

Experience 2. “There is air in the glass and it is invisible”

The children are invited to lower the glass into the jar of water again, but now they are invited to hold the glass not straight, but slightly tilted. What appears in the water? (Visible air bubbles). Where did they come from? Air leaves the glass and water takes its place.

Conclusion: Air is transparent, invisible.

Experience 3: "What's in the bag?"

The teacher shows the children an empty plastic bag. What's in the package? (children's answers). And now? (the teacher turns away, fills the bag with air, shows it to the children) (children's answers). Why can't we see air?

Conclusion: the air is transparent. What else is transparent? (Window glass, aquarium, glasses, light bulb)

Experience 4. "Air is elastic"

The teacher invites the children to catch the air in the bag, touch it with their hands. What do they feel? (As if there is something in the bag, the bag collapses when you press on it with your fingers, it returns to its shape when you put your fingers down).

Conclusion: air is elastic. Air can be caught and locked where? - in the ball, ball, tire. The trapped air softens the blow, so tires are inflated with it; he makes the ball bounce. Compare how an inflated and not inflated ball bounces.

Experience 5. "Air is everywhere."

Take a lump of earth and lower it into a glass of water. Watch for air bubbles.

Conclusion: There is air in the soil.

Take a dry stone and lower it into a glass of water. Watch for bubbles to appear.

Conclusion: There is air in the stone.

Educator. We can also feel the air. How? (we blow on the palm). What happens? (wind)
Teacher: What is wind?
Children: Wind is the movement of air.
Educator: Come on, now we all quietly get up for a physical minute. It's called Wind.
Fizminutka "Wind"
The wind is blowing in our face, wave your hands in the face
The tree swayed, hands up, tilts
The wind is quieter, quieter, squat
The tree is higher, higher, lifting up on toes

Experience 6. "Fan"
And now let's wave the fan in front of the face. What do we feel? Why did people invent the fan? And what has replaced the fan in our lives? (Fan, air conditioner).
Conclusion: we feel the air.

Educator: Where is the wind used by man?
Children: Sailing boats, windmills.

Experience 7 "We breathe air."

A glass of water and a straw will help us make sure of this. We inhale air through the nose, exhale through the straw into the water.
What do we see? - bubbles. What does it mean?

Conclusion: We breathe air. And all living beings on earth breathe air: plants, fish in the water.

Educator: Guys, I have musical instruments in my hands.

Experience 8 "Pipe"
Blow the pipe and it will play.

Conclusion: Air can be heard. Sound is produced when the air trembles.

Experience 9 "Soap bubbles"
Blow soap bubbles, balloons.

Conclusion: Soap bubbles and balloons fly easily - the air is light.

Educator: Inhale the air with your nose. What does he smell like?
Children: The air has no smell.
Teacher: Breathe in through your mouth. What does it taste like?
Children: The air has no taste.

Summarizing

What properties of air did you learn today?
(Invisible, transparent, resilient, light, you can hear it)
Where can you find air?
Why is the ball bouncing?
Why can't we see air?
What is wind?

Educator: Children, so we got acquainted with the invisible air. We will find out more later:
* Why are there waves on the sea, on the river?
* Why do birds, planes, rockets fly and do not fall?
* The air is cold, warm.
* The air is clean, dirty. What does it depend on?
Do you want to know about it? See you in our lab then!

Tamara Kuchenkova
"Invisible Air" Abstract open class in the senior group

Target:

1. To form children's ideas about air and its properties in the life of man, animals, plants.

2. make children's ideas about the wind, arouse interest in conducting experiments.

3. Develop the ability to reason logically, evoke a feeling of love for others.

4. Raise a sense of responsibility for nature, entertain and emotionally set up children.

Previous work:

Observation while walking for the wind, clouds; boat design; reading fiction.

Equipment:

Transparent glass glass, metal spoon, transparent deep container with water. Air balloons, straws for cocktails, soap bubbles, foam and paper boats, large containers of water, polyethylene napkins, room fan, screen for puppet theater, Pinocchio doll, sheets of paper, colored pencils.

Literature:

N. E. Ryzhova "Not just fairy tales".

V. Kolomina "Educating the basics ecological culture in kindergarten".

O. R. Galimov "Physics for preschoolers

O. V. Dybina, N. P. Rakhmanova, V. V. Shchetinina "Unknown near".

A. Holden "The world around" a series "Fun Lessons"

Lesson progress:

Vospi.: - Guys, listen carefully and guess riddle:

We need it to breathe

To inflate the balloon.

With us every hour

But it is invisible to us!

Children: -Air.

Resp.: - That's right. air. Today we will talk about air Let's do experiments like real scientists. And for this we have a laboratory. (shows)

Bur.: Hello guys!

What are you going to do here?

Vosp.: -The guys and I want to talk about air.

Bur.: -O air? And who saw this air? Maybe he doesn’t exist at all! Personally, I have never seen air and you guys?

Vosp.: - Wait, wait, Pinocchio! I'm here too I didn't see the air but I know that he is always around us.

Bur.: Oh, you know everything! And I don't believe you! Here, prove to Yu that this one there is air in this room.

Vosp.: -Guys, let's prove Pinocchio that there is still air(experiment 1 with sachets)

Vosp .: -What do the guys have in our bags?

Children:-Air.

Question: What is he like? Do we see him? Why can't we see air? Why is it called invisible? (children's answers)

-The air is transparent so you can see everything through it. Look. What else is transparent? Let's find transparent objects in our room

(aquarium, windows)

(goes to the window)

Look at how transparent the glass is, you can see everything through it - and other houses, cars on the street, and trees, and now let's go together to our laboratory, I want to show you one more experience

(shows a glass)

Guys, do you think this glass is empty? If there is anything in it? (listens to children's responses)

Bur.: Well, what's interesting here? It is clear to everyone that there is nothing in the glass. Let's put something in there or put it.

Vosp .: -You say there is nothing in the glass, but we will check it now! (experiment 2 with a glass).

Vosp .: -Well, the guys made sure that the glass is not empty, it has air:

Bur.:- Eka unseen, air! I may have known before there is air and just told everyone. I also remembered how to see air. Here, listen to me. Once I was treated tasty water and gave me a straw. Of course, I not only drank, but also blew bubbles through a straw. That was great!

Play: -Guys, let's also blow bubbles from a straw

Take a straw each and go to a vessel of water. (experiment 3 - with straws)

What comes out of the water bubbles:

Children: -Air

Vosp .: -And what bubbles can you still blow?

Children: Soapy

Vosp .: -Let's blow bubbles too

(children take "bubble" and let them in)

Vosp.: - Pinocchio, what do you think is inside the soap bubbles?

Bur.: I know, of course, soap!

Vosp .: - Guys, are Pinocchio right? Why? Of course, in every bubble inside there is air!

Bur.: - Air, soap, what's the difference! You are better for me tell: and I, and the guys and all people breathe through the nose. Correctly?

Vosp .: -Guys, let's show Pinocchio how our noses breathe. (experiment 4 with a napkin).

When we just exhale and inhale air do we see it?

Children: -Not!

Vosp.:- And with a napkin you can see (Yes)

And you can also see how we breathe in winter - steam comes out of our mouths.

Bur.: Guys, do you know what animals breathe?

Children: They also have spouts.

Bur.: And the dog, if it breathes hot through its mouth, I saw it myself? And how do plants breathe, where are their noses then? (children's hypotheses).

Vosp .: -And plants don’t have any noses. But on the leaves they have small holes, they are difficult to see. It is through them that all plants breathe, and indoor ones too. That's why we dust the leaves and mine them.

Bur.: So the bell, and the birch, and the oak - everyone, everyone needs air?

And I didn't know about it.

Vosp.:-Of course, Pinocchio, all living beings need air.

Really guys?

Here we breathe with our noses, but what else can we feel with them?

Children: - We can smell.

Play:- A the air smells?

(children's answers)

Vosp .: -But how does it happen when pies are baked in the kitchen, we are in group smell them?

(children's answers)

-Air moves and brings to our noses, although he the air is odorless.

What other odors can you tolerate? air?

Can it air carry sounds?

(children's answers)

(experiment 5 with a glass and a spoon)

From a blow with a spoon, the glass of the glass begins to tremble, finely and often. From this begins to tremble, to move air around the glass. Gradually this trembling air reaches our ears and we hear this ringing. Means air, can carry sound.

Bur.: - And I know where you can find a lot air - in balloons? And so they are called - air.

Vosp .: - Well, that Pinocchio, we convinced you that there is air?

Bur.: Yes, I understand that air surrounds us everywhere and we breathe it.

Idle time thought that since it is not visible, then it is not there. And now I'll go to puppet show to my friends and tell them about air. And I want to give you these air balloons(gives children a box of balloons).

Vosp .: -Guys, let's check if there are many air in your chest let's inflate balloons (children inflate balloons and blow them).

You must have seen how air The balls are released and they fly away in the sky. You must know that this is harmful to nature. Why do you think (children's answers).

Sooner or later, the balloons will either burst or come out of them. air and they will land on land or in the sea, and then they may be swallowed up by animals or fish, and from this they will die. And we will not let the balls go on the street! But in group. where we can pick it up and put it away and put it away we can do it. Let's now, at my command, let's unanimously release our balls and see what happens. (I release the balls, it comes out air)

What do you feel?

Children: -Wind.

Vosp .: -Remember what we just said that you can’t throw balls. And we will collect them now.

(collect balls)

(fan turns on)

Vosp .: -Oh, what are these, the balls are no longer flying, but the wind is getting stronger? And it doesn’t look like it’s wind from small balls.

(Carlson flies in)

Carl: Hello, boys and girls.

(children greet Carlson)

Vosp.: - Hello, Carlson. Is it you who raised the wind?

Tell me how you do it

Carl: I have a propeller on my back. I turn on the motor, the propeller spins and it turns out the wind. Here I will show you a fan, it is exactly the same as my propeller. Look!

(includes fan)

Vosp .: -Guys, what do you think, why do we need a fan?

(children's answers)

Yes a fan is needed hot weather to refresh air. And let's show Carlson how we ourselves can make wind (experiment 6 with boats)

Guys, here we are air from the balls and the wind was obtained. Then they blew on the boats and the wind also turned out. -What is the wind?

Vosp.: -Wind is movement air.

On a walk, we often observe if there is wind outside. How can we see it?

(children's answers: branches, leaves of trees sway, clouds run quickly across the sky)

Now let's draw the wind. Go to the tables.

Carl: -I also want to draw with children.

Vosp .: And you, Carlson, will draw on a large sheet, on the board.

(draw) (Carlson draws on the board)

Vosp.: -Children, let's see how Carlson drew. Did he draw correctly? (analysis of Carlson's drawing).

(total):-Today we learned about air. What have we learned?

What air part of nature. It is everywhere around us, we breathe it.

-air is invisible, transparent - air can move.

And another very important property air. It itself is odorless, but can tolerate odors. We don't hear air, but when it moves, it can carry sounds.

We all need air. There is no life without him.

In our online lesson on the world around us, we will talk about what we, nature, planet Earth would not exist without. Yes! This is air. What is air?...

Air and the properties of air

Air is a mixture of gases: nitrogen, oxygen, carbon dioxide and others.

Gases have no shape. They spread in all directions and fill the entire available volume.

Air shell of the Earth atmosphere- protects us from destructive cosmic rays, from overheating by the heat emanating from the Sun, from hypothermia.

Layers of the atmosphere:

Air is necessary for all living things to breathe and to create organic substances.
We watch an informative video from 5.55

What are the properties of air?

More about properties.

Now you see everything that is around you: walls, a computer, a closet, outside the window - houses, trees, clouds. Can we see air? AT Do you believe that air is everywhere around us?Does he exist at all? Maybe they invented it? Shall we prove it?

Study 1 .

Take a straw and dip it into a glass of water. Lightly blow into the straw. What has appeared? will appear air bubbles.

Conclusion: With the help of vision, air can still be detected in some cases.

Look at houseplants. What color are they? What about your walls? What color do you think the air is?
We open the first property of air: the air is invisible and colorless .

Study 2 . Now take a deep breath, what do you feel?Does the air smell like anything? But what about the smells in the confectionery, pharmacy? …We smell when particles of a substance enter our nose.

Conclusion: Pure the air has no smell.

Study 3 . Can you taste the air? Lick it.What properties of air will we discover?

Conclusion: the air has no taste

Study 4. Pick up a book. What form is it? Now try to take the air in your hands. Happened?Does air have a shape?

Conclusion: air has no shape.

Research 5.Air is elastic

Take the ball, squeeze it with your hands. Hit the ball on the floor. What are you watching? What property of air was discovered?

Now look at these two balls. Which one is more elastic? Why?

Can I make the first ball as elastic as the second one? What do I need to do?…. That's right, add air. And what happens to the ball when we add air? ...... (Air is compressed).

You must have a bicycle. What property of air is used when inflating the chamber of a bicycle wheel with a pump? ..... also jumping on sports bikes is done just because of the air in the tires.

Where else is this property used?

Research 6. Air is lighter than water, that is, less dense than water.

Take a cup of water. Try drowning a tennis ball in it. What are you watching? What property of air was discovered?

This is why you are not afraid to swim with a lifebuoy on.

Research 7. Air is a poor conductor of heat.

Why do houses have double-paned windows? What is between the frames? What property of air is manifested here?

Indeed, between these double glazing there is air that does not let the cold in and the house becomes much warmer. Since air has a low density, it conducts heat poorly.

If air is a poor conductor of heat, why does the ground remain warm under snow and plant roots do not freeze? H the same warms the earth, is it snow?

Between the snowflakes is air, it does not let the cold through.

Think about how the birds sit when it's cold outside? Why?…. And what happens to animal fur by winter?

Animal fur, bird feathers do not warm themselves, but warms the air between them. When it's cold, the animals raise their wool, the birds flutter, and the person puts on a warm sweater, a fur coat.

Research 8. Expands when heated

Why do people in the bath rise to the shelves, closer to the ceiling, to take a steam bath? Why are the batteries in the rooms installed below, under the window? What happens to hot air?

Yes, when the air heats up, the air expands, that is, it becomes lighter and rises.

Now can you explain how a hot air balloon flies?

What about Chinese lanterns?

Is it possible to have the same temperature: day and night? winter and summer? at the poles and at the equator?

What happens to warm air? (rises). What takes up the vacant space? (Cold air).

And this means that on Earth there is a constant movement of air, but simply the wind blows.

Wind is the movement of air.

Winds bring both benefit and harm.

Imagine for a moment that there is no wind on Earth. There is no wind in our industrialized city, where there are plants, factories, mines, cuts, explosions. What will happen?

Chimneys from plants and factories throw smoke high into the sky. Strong winds are blowing up there. They pick up clouds of smoke and tear them to shreds, scatter them, mix with clean air, quickly reduce the danger of poisonous gases. Tall chimneys keep trouble away from people living nearby.

There are winds that bring a lot of trouble.

How does a person use the properties of water

Man has long learned to use the power of air as a source of energy.
He invented sail which allowed him to travel.

Already 2-3 thousand years ago, the Egyptians sailed on mediterranean sea on completely perfect sailing ships.
Built in the Middle Ages wind wheels for housework.

However, even in modern times, the wind turbine plays everything big role, because unlike other sources, it does not pollute the atmosphere.

One of the ways to move through the air is a balloon filled with a gas lighter than air or simply heated air. The beginning of the era of aeronautics should be considered the year 183, when the Montgolfier brothers took to the air on hot-air balloon filled with hot air.

You cannot rely on water reliably - it is liquid. However, the water skier succeeds if he develops sufficient speed. Air is even less dense than water. But if you develop a high speed, then it turns out you can rely on it. This discovery allowed the creation of more advanced aircraft.

Ability to travel by air aircraft due to the fact that air has a buoyant force. For example, if you fill a balloon with a lighter gas - hydrogen, then they will fly up.

The parachute can glide through the air due to the density of the air.

You know that when water is heated, it turns into steam, a gaseous state, and if the steam is cooled, it will turn into a liquid state again.

It turns out that any gas can also be turned into a liquid if cooled. Only this requires a very low temperature.

Carbon dioxide , cooled to a solid state, is used to freeze food and is called dry ice. And it melts at -78 degrees C.

Liquid nitrogen is formed at a temperature of -196 gr.S. It is used in medicine.

Clean oxygen used for breathing patients. They are filled with scuba gear for underwater breathing. oxygen masks are on planes for emergencies.

And liquid oxygen is needed to oxidize the fuel spaceships. After all, without oxygen, not only breathing is impossible, but also combustion.

We all understand that our planet simply needs air. It should be protected!

Praveen Kadambari

Why can't we see gases?

I'm not sure what causes the gas molecules to be invisible. This question may look stupid, but I really want to know the story behind this.

Shroedinger `s cat

Who said we can't see gas molecules?

Bernhard

@Amazing, that's not exactly an explanation, right?

Carl Wittoft

@iamnotmaynard This site is mostly valid, albeit somewhat confusing. The blue sky is due to the scattering of blue, and not the absorption of other colors (as, for example, in the case of a blue sheet of paper). If there were no scattering, the sun would be brighter and the rest of the sky would appear black. However, the unscattered light (or sunset colors) is not the result of the color of the atmosphere, but is only the remnants of sunlight after some colors have been removed from the direct path.

Henk Langeveld

Ask yourself, "invisible to whom? Visibility is subjective to the observer.

Answers

DavePhD

(photo courtesy of Ephram Goldberg)
[Note: the leftmost ampoule is cooled down to -196°C and covered with a white layer of frost .]

N O 2 "role="presentation" style="position: relative;"> N N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> O N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> 2 N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;">N N O 2 "role="presentation" style="position: relative;">O N O 2 "role="presentation" style="position: relative;">2 good example colored gas. N 2 O 4 " role="presentation" style="position: relative;"> N N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> 2 N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> O N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> 4 N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;">N N 2 O 4 " role="presentation" style="position: relative;">2 N 2 O 4 "role="presentation" style="position: relative;">O N 2 O 4 " role="presentation" style="position: relative;">4(colorless) exists in equilibrium with N O 2 "role="presentation" style="position: relative;"> N N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> O N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> 2 N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;">N N O 2 "role="presentation" style="position: relative;">O N O 2 "role="presentation" style="position: relative;">2, At a lower temperature (on the left in the photo from Wikipedia), N 2 O 4 " role="presentation" style="position: relative;"> N N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> 2 N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> O N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;"> 4 N 2 O 4 " role="presentation" style="position: relative;"> N 2 O 4 " role="presentation" style="position: relative;">N N 2 O 4 " role="presentation" style="position: relative;">2 N 2 O 4 "role="presentation" style="position: relative;">O N 2 O 4 " role="presentation" style="position: relative;">4 is preferred, while more high temperature N O 2 "role="presentation" style="position: relative;"> N N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> O N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;"> 2 N O 2 "role="presentation" style="position: relative;"> N O 2 "role="presentation" style="position: relative;">N N O 2 "role="presentation" style="position: relative;">O N O 2 "role="presentation" style="position: relative;">2 is preferred.

In order for a gas to have a color, an electronic transition is required corresponding to the energy of visible light.

If our eyes worked around 100 nm, we would live in a very dark world, almost all of the light would be absorbed by the atmosphere. The same if they worked at 10 micrometers. But our eyes evolved to use the light that was available to them; and this light was between 400-700 nm; right in the middle of this absorption drop (obviously you need to look at the nitrogen and oxygen absorption spectra to get the full picture).

So the reason why we can't see ordinary gases; because evolution has optimized our eyes to work that way. If we evolved in an atmosphere composed mostly of chlorine gas, I would bet we would still be asking, "Why can't we see gases?" and someone would come up with counterexamples of how (in their world) rare gases, water vapor, oxygen and nitrogen were seen.

In some other part of the electromagnetic spectrum, air may be visible.

One of the reasons why the eyes became sensitive in the "visible" spectrum is that the air there does not absorb. Otherwise the eyes would be useless: you would see nothing but air. Our eyes can only tell us what's going on around us if they use the part of the spectrum where the air doesn't absorb.

Carl Wittoft

This, as I said, is only part of the story. It turns out there are only certain wavelength ranges that the classes are sensitive to. chemical substances that animals can produce. There are other spectral bands with high atmospheric permeability, but no organic compound to discover them.

@CarlWitthoft You are correct. I didn't go into detail on this, but will probably update my answer.

DavePhD

@mpv nitrogen tetroxide is not visible, nitrogen dioxide is.

rob

One factor to keep in mind is that for a low density material with relatively weak interactions with light, the total mass of the column through which the light travels will have great importance in perceived color. For example, if you fill a white tub with water, you will notice that the centimeter column of tap water (or from your glass of water) is transparent, while the decimeter column at the bottom of the tub is transparent. distinctly blue.

You can see the same effect when you look at a green or brown mountain from a distance of several tens of miles: greens and brown spots are washed out by the blue of many tons of air.

wbeaty

Why liquids invisible? And why do gases look like silvery drops? (... asks a creature that has spent its entire life underwater.)

Gases are transparent, invisible. Living at the bottom of an "ocean of air" can give certain air-breathing organisms a distorted perspective.

If we spent our lives in a vacuum, we would think that air and water were transparent liquids. We would notice that air bends light much less than water. In a vacuum, a clean bag of air will behave differently than a lens compared to a clear bag of water.

Actual classroom demo: Get an aquarium full of water. Fill up the water balloon. Now keep the ball submerged in the aquarium and let it release the water. See nothing? There is not. This clearly proves that water is invisible.:) And if we had a gas-filled environment and then released the contents of the gas-filled cylinder, we could prove to ourselves that the gas is invisible. Not? We are air fish living at the bottom of the nitrogen ocean and firmly convinced that gas is an invisible material.

Gas can be very noticeable. The sun is all made of gas and completely opaque. Inside sunlight, the particles (photon) travel only centimeters (in the very deep) kilometers (closer to the surface) before they are absorbed. Not very different from other "particles" of local gas. So you can't see the sun in the light (you can use acoustic waves as a subsurface diagnostic, but that's another story).

What we call the "solar surface" is the layer far away where the gas becomes rarefied enough to become transparent. There photons run away like sunlight. The gas there is actually much less dense than the transparent air around us because it is composed of almost pure hydrogen (making it completely opaque to visible light if enough hydrogen atoms grab an extra (second) electron, a process only understood in 1940s)).

A small part of a very small part that hits the earth is dissipated in our atmosphere; those that bounce off your eye form blue sky you see. Blue not because they change energy (color), but only because more photons scatter in blue than in red - that's why the sun shows red at sunset because more blue is emitted directly into your eye.

A good question, because the transparency of gases seems illogical to us. This is why "radiative transport in stellar atmospheres" is an advanced topic in astrophysics courses. The light that comes from the stars is our main diagnostic to understand them, but interpreting this light requires a good understanding of the opacity of the stellar gas. Google this topic and read my notes...

Lee Ryan

The sun produces its own light, which could overwhelm any semblance of light coming from the other side, even if it is completely transparent.

Richard Tingle

It is worth noting that (overwhelmingly) the sun is not a gas. This is plasma; the fourth state of matter, where the electrons are completely separated from the nuclei

Rob Rutten

@Richard Tingle - Yes, indeed, only in the lower part of the solar atmosphere, exactly in the layer where it exits visible light, the gas (mostly hydrogen molecules) is neutral, with one tenth of a ppm having a second electron and controlling the output solar radiation we see. At greater depths from the sun, the gas becomes more and more ionized; in the nucleus it is indeed fully ionized (all electrons are off). Still "gas" as it still obeys the simple "law ideal gas"P = NkT.

Richard Tingle

To say that a plasma is a type of gas is like saying that a gas is a type of liquid because it has no certain form. They are very different animals; it is obvious that they behave very differently in electrical and magnetic fields, but more subtly they have collective interactions at a great distance and can move "like a mass", while gas interactions are always interactions of two particles. See this wiki page in particular for the section explaining the difference between gas and plasma: en.m.wikipedia.org/wiki/Plasma_(physics)

Henk Langeveld

Visibility is subjective

Visibility is subjective, you need observer .

You asked for history. It starts with our earliest ancestors who developed sensors that are sensitive to electromagnetic radiation.

What kind of sensors and what kind of radiation? No matter what happens.

At the beginning? Whatever radiation was available, anything that entered the atmosphere with enough energy to reach the Earth's surface.

As the atmosphere changed, the sensors adapted to the radiation that had to pass through.

Over time, these sensors evolved into eyes. As they did with many other species.

Rijul Gupta

I just had to paste here!

In expanding your question, you are asking what

I'm not sure what causes gas molecules to be invisible

Well, all "molecules" are invisible to our eyes, we just don't have permission to see them, if you have an atomic force microscope, you can see them like this

However, you can see a lot of gas in general, as @DavePHD clearly demonstrated!

If you are still going to talk about the fact that you can see practically all solids or liquids, and not all gases, you should look at people who hit themselves against mirrors or glasses, as they too become invisible to us in various cases.

While nearly all solids and liquids are organized enough to at least reflect light, gases are too scattered to do so! The only property that allows gases to become visible is the absorption or emission of photons, if at the time of absorption the additional light is in the visible range we can see the gas, and if the emitted light is in the visible range we can see it, otherwise we we just can not with our eyes!

In the last paragraph, don't think of fog or other similar things that look like gases and say they reflect! There are other phenomena that play out there, and besides, the fog is not a gas! Reflection only comes from gases when it is impure and more colloidal in nature as smoke particles make it black/gray/white in smoke!

David White

The answer has a biological component. Essentially, the environment selects attributes that increase the likelihood that a species will be successful in passing on its genes to future generations. On this basis, if a sense such as sight develops in a species, it will evolve in a way that maximizes the usefulness of that sense. For earth's atmosphere eyes various kinds"tuned" to specific wavelengths of light that are not absorbed by the atmosphere because those wavelengths give these species the most information about environment and therefore increase their chances of reproduction.