Description: War Thunder is a next generation military MMO game dedicated to...
MBOU "Troitsk secondary school" Physics lesson in grade 7 on the topic: "Atmosphere and atmospheric pressure" Physics teacher: Rudneva N.A. year 2012
"It's amazing to live in an ocean of air,
Blue, huge, clean, "drink" it and not drown,
Without it, without the ocean, life would be very strange, however, not even strange: it simply wouldn’t exist!”
Lesson topic: Earth's atmosphere. Atmosphere pressureThe purpose of the lesson: Consider the structure of the Earth's atmosphere, verify the existence of atmospheric pressure and learn how to use the knowledge gained to explain physical phenomena.
“The atmosphere animates the Earth. Oceans, seas, rivers, streams, forests, plants, animals, man - everything lives in the atmosphere and thanks to it. The earth floats in an ocean of air; its waves wash both the tops of the mountains and their foot; and we live at the bottom of this ocean, covered by it from all sides, penetrated through it ... None other than it covers our fields and meadows with greenery, nourishes both the delicate flower that we admire, and the huge, centuries-old tree that stores work sunbeam in order to give it to us later"
Camille Flammarion (19th century French astronomer)
The ancient Greeks thought that the air around us is evaporated water and called the shell surrounding the planet ATMOSPHERE Atmos-vapor Sphere - ball Composition of the atmosphere Earth's atmosphere consists of a mixture of gases: nitrogen, oxygen, argon. The amount of other gases in the air is negligible. These gases include carbon dioxide, hydrogen, neon, helium, krypton, radon, and others. As well as variable constituents of the atmosphere, such as nitrogen oxides, sulfur, carbon monoxide, ammonia, sulfur, hydrogen sulfide, water and dust.
In its structure, the air ocean resembles a house, which has its own floors.
Contains more than 80% of the total mass atmospheric air and near 90% of all water vapor in the atmosphere.
The first "floor" is the troposphere.
This layer extends on average up to 11 km above sea level, and the temperature in it decreases with height. The troposphere is the birthplace of clouds. Most of the weather phenomena we observe are formed in this layer.
The second "floor" is the stratosphere.
It is located between the 11th and 55th km above sea level. The stratosphere is 1/5 of the atmosphere by mass. Here is the realm of cold, with an approximately constant temperature of -40˚С.
Here, only occasionally, so-called mother-of-pearl clouds appear, consisting of the smallest ice crystals and drops of supercooled water. The sky of the stratosphere is black or dark purple.
The third "floor" is the mesosphere.
This layer occupies the space between the 55th and 80th km from the Earth. The air is very thin here. Its pressure is approximately 1/25,000 of normal atmospheric pressure. It is in this layer that the ozone gas is located, which protects all life on Earth from the harmful effects of the ultraviolet rays of the sun.
Sometimes misty noctilucent clouds appear in the mesosphere, which are visible only at dusk.
Fourth floor - ionosphere
At altitudes above 100 km, the proportion of light gases increases, and at very high altitudes, helium and hydrogen predominate; many molecules dissociate into separate atoms, which, being ionized under the influence of hard solar radiation, form the ionosphere. Lightning and polar lights appear here.
The fifth "floor" is the thermosphere.
The air in the thermosphere is even more discharged. Here is an unprecedented heat: 1000-2000˚С. However, if a person were here, he would not feel this heat, because the air density in this layer is extremely low. In the thermosphere, pearl clouds, auroras, powerful electric currents are formed that cause disturbances magnetic field Earth.
Thermosphere
Thermo With fera
The sixth "floor" is the exosphere,
i.e., the outer shell of the atmosphere. The height of this layer is 500-600 km. The air here is discharged even more than in the thermosphere. This "floor" is also called the "scattering layer", because the air molecules here, moving at great speeds, sometimes fly away into interplanetary space.
The air shell of the Earth performs various functions
Dawns
Polar Lights
Has 6 layers:
Troposphere
Stratosphere
Mesosphere
Ionosphere
Thermosphere
exosphere
Composition of air:
oxygen
Radiation protection
Meteor protection
UV protection
Scatters the light
Transmits sound
Airlines routes
Temperature protection
Long distance radio
Essential for breathing
Wind energy
I have six servants,
Agile, remote.
And all that I see around -
I know everything from them
They are at my behest
Are in need.
They are called: How and Why, Who, What, When and Where.
… But I have a dear friend,
Young person.
Hundreds of thousands of servants serve her, -
And there is no rest for everyone!
She runs like dogs
In bad weather, rain and darkness
Five thousand Where, seven thousand How,
One hundred thousand Why!
R. Kipling
Experiments have established that under normal conditions, the mass of air with a volume of 1 m³ is 1.29 kg.
Calculate the weight of air?
P=mg=9.8N/kg∙1.29kg≈13N
Why do we not feel that a vertical column of air is pressing on us?
Bodies do not collapse under the action of atmospheric pressure. This is due to the fact that they are filled with air inside. Air from inside and outside presses equally.
Our body is designed in such a way that we do not feel atmospheric pressure, since the pressure inside us is equal to the pressure of the atmosphere.
Want to improve your computer skills?
If an Excel workbook contains so many sheets that their titles don't fit at the bottom of the sheet, it's difficult to switch between sheets. Of course, you can use the navigation buttons between sheets or the list of sheets that appears when you right-click on the navigation buttons (the active sheet is marked with a checkmark). But we can use another way to switch between sheets - adding a table of contents to the book.
Read new articles
The lesson can be fruitful and joyful, in one breath, or it can drag on sluggishly and boringly, exhausting the children and the teacher and not bringing satisfaction to anyone. And the reason for this is not only methodological errors, features of the material and class. Perhaps, even to a greater extent, the reason must be sought in the emotional background of the lesson, which turned out to be unfavorable. Creation emotional background is a task that inevitably confronts any teacher and requires his attention and efforts. How to create a positive lesson background?
How to capture the attention of a student in the digital age, when the flow of information completely absorbs a person? Probably, many are familiar with the situation when there is a lesson, and the students look at the phone screen and do not want to do anything else. How to capture the attention of students and make the lesson interesting? Let's take a look at a few ways to create interest in the lesson.
slide 2
Presentation on the topic: ATMOSPHERIC PRESSURE
slide 3
Atmospheric pressure is the pressure force of the air column per unit surface area (the number of kg per 1 sq. cm). It is known that normal pressure acts on a square centimeter of our body as a weight of 1.033 kg. However, atmospheric air pressure does not bother people, since dissolved air gases balance everything in tissue fluids.
slide 4
ATMOSPHERIC PRESSURE (Greek atmos - steam) - the gravity of the air column from its upper limit to the earth's surface or ground objects at a given altitude level. The weight of 1 liter of air at the level of the World Ocean is about 1.3 g, and its pressure reaches 1033 g/cm2. At sea level at a latitude of 45 ° at a temperature of 0 ° C Atmospheric pressure is equal to the weight of a mercury column of 760 mm or 1013 mblr, which is taken as normal pressure the globe. For every 10 m increase in altitude, atmospheric pressure decreases by 1 mm or 1.3 mlbar, as measured by a barometer. Pressure depends on changes in temperature, and therefore on the time of day, on the change of one or another air masses(cyclones decrease, and anticyclones increase).
slide 5
Changes in atmospheric pressure within the atmosphere:
slide 6
Atmosphere - the air shell of the Earth / several thousand kilometers high /.
Slide 7
Having lost the atmosphere, the Earth would become as dead as its companion the Moon, where either sizzling heat or chilling cold reign alternately - + 130 C during the day and - 150 C at night.
Slide 8
According to Pascal's calculations, the Earth's atmosphere weighs as much as a copper ball with a diameter of 10 km would weigh - five quadrillion (5000000000000000) tons!
Slide 9
Story
The presence of atmospheric pressure confused people in 1638, when the idea of the Duke of Tuscany to decorate the gardens of Florence with fountains failed - the water did not rise above 10.3 meters. The search for the reasons for this and experiments with a heavier substance - mercury, undertaken by Evangelista Torricelli, led to the fact that in 1643 he proved that air has weight. Together with V. Viviani, Torricelli conducted the first experiment on measuring atmospheric pressure, inventing the Torricelli tube (the first mercury barometer) - a glass tube in which there is no air. In such a tube, mercury rises to a height of about 760 mm.
Slide 10
Variability and impact on weather
On the earth's surface, atmospheric pressure varies from place to place and over time. Especially important are the weather-determining non-periodic changes in atmospheric pressure associated with the emergence, development and destruction of slowly moving regions. high pressure(anticyclones) and relatively fast moving huge eddies (cyclones), in which low pressure prevails. There were fluctuations in atmospheric pressure at sea level in the range of 641 - 816 mm Hg. Art. (inside the tornado, the pressure drops and can reach a value of 560 mm Hg). Atmospheric pressure decreases as altitude increases, since it is created only by the overlying layer of the atmosphere. The dependence of pressure on height is described by the so-called. barometric formula. On maps, pressure is shown using isobars - isolines connecting points with the same surface atmospheric pressure, necessarily reduced to sea level. Atmospheric pressure is a very variable weather element. From its definition it follows that it depends on the height of the corresponding column of air, its density, on the acceleration of gravity, which varies with the latitude of the place and the height above sea level.
slide 11
Standard pressure
In chemistry, since 1982, the standard atmospheric pressure, according to the IUPAC recommendation, is a pressure equal to 100 kPa. Atmospheric pressure is one of the most significant characteristics of the state of the atmosphere. In a resting atmosphere, the pressure at any point is equal to the weight of the overlying column of air with a unit cross section. In the GHS system 760 mm Hg. Art. equivalent to 1.01325 bar (1013.25 mbar) or 101325 Pa in international system units (SI). The equation of statics expresses the law of pressure change with height: -∆p=gρ∆z, where: p - pressure, g - free fall acceleration, ρ - air density, ∆z - layer thickness. It follows from the basic equation of statics that as the height increases (∆z>0), the change in pressure is negative, that is, the pressure decreases. Strictly speaking, the basic equation of statics is valid only for a very thin (infinitely thin) air layer ∆z. However, in practice it is applicable when the change in altitude is sufficiently small relative to the approximate thickness of the atmosphere.
slide 12
slide 13
baric stage
The height to which it is necessary to rise or fall in order for the pressure to change by 1 hPa (hectopascal) is called the baric (barometric) stage. The baric stage is convenient to use when solving problems that do not require high accuracy, for example, to estimate pressure from a known height difference. From the basic law of statics, the pressure stage (h) is: h=-∆z/∆p=1/gρ [m/hPa]. At an air temperature of 0 °C and a pressure of 1000 hPa, the baric level is 8 m/hPa. Therefore, in order for the pressure to decrease by 1 hPa, you need to rise by 8 meters. With increasing temperature and increasing altitude above sea level, it increases (in particular, by 0.4% for each degree of heating), that is, it is directly proportional to temperature and inversely proportional to pressure. The reciprocal of the baric step is the vertical baric gradient, that is, the change in pressure when raising or lowering 100 meters. At a temperature of 0 °C and a pressure of 1000 hPa, it is equal to 12.5 hPa.
Slide 14
Adjustment to sea level
The reduction of pressure to sea level is carried out at all meteorological stations that send synoptic telegrams. To make the pressure comparable at stations located at different heights, the pressure reduced to a single reference mark - sea level is applied to synoptic maps. When reducing pressure to sea level, the abbreviated Laplace formula is used: z2-z1=18400(1+λt)lg(p1/p2). That is, knowing the pressure and temperature at the level z2, one can find the pressure (p1) at sea level (z1=0). Calculation of pressure at altitude h from sea level pressure Po and air temperature T:P = Poe-Mgh/RT where Po - pressure Pa at sea level [Pa]; M - molar mass of dry air 0.029 [kg / mol]; g - free fall acceleration 9.81 [m/s²]; R is the universal gas constant 8.31 [J/mol K]; T- absolute temperature air [K], T = t + 273, where t is the temperature in °C; h - height [m]. At low altitudes, every 12 m of ascent reduces atmospheric pressure by 1 mm Hg. Art. At high altitudes, this pattern is violated.
slide 15
Barometer
Atmospheric pressure is measured in millimeters of mercury (mmHg). To determine it, they use a special device - a barometer (from the Greek baros - gravity, weight and meter - I measure). There are mercury and non-liquid barometers.
slide 16
Mercury Aneroid
barometers
Slide 17
Barometer
Aneroid barometer: 1 - metal box; 2 - spring; 3 - transmission mechanism; 4 - arrow-pointer; 5 - scale
Slide 18
The Torricelli Experience
The value of 760 mm was first obtained in 1644 by Evangelista Torricelli (1608-1647) and Vincenzo Viviani (1622-1703) - students of the brilliant Italian scientist Galileo Galilei. E. Torricelli soldered a long glass tube with divisions from one end, filled it with mercury and lowered it into a cup with mercury (this is how the first mercury barometer was invented, which was called the Torricelli tube). The level of mercury in the tube dropped as some of the mercury spilled into the cup and settled at 760 millimeters. A void formed above the column of mercury, which was called the Torricelli void. E. Torricelli believed that the pressure of the atmosphere on the surface of the mercury in the cup is balanced by the weight of the mercury column in the tube. The height of this column above sea level is 760 mm Hg. Art.
Slide 19
Slide 20
Conclusion:
Torricelli noticed that the height of the mercury column in the tube changes, and these changes in atmospheric pressure are somehow related to the weather. If you attach a vertical scale to a tube with mercury, you get the simplest barometer.
slide 21
WHAT WOULD HAPPEN ON EARTH if the air atmosphere suddenly disappeared?
slide 22
On Earth, a temperature of approximately -170 ° C would be established, all water spaces would freeze, and the land would be covered with an ice crust. - there would be complete silence, since sound does not propagate in the void; the sky would become black, since the color of the firmament depends on the air; there would be no twilight, dawns, white nights. - the twinkling of the stars would stop, and the stars themselves would be visible not only at night, but also during the day (we do not see them during the day due to the scattering of sunlight by air particles). - Animals and plants would die. ...some planets solar system also have atmospheres, but their pressure does not allow a person to be there without a space suit. On Venus, for example, atmospheric pressure is about 100 atm, on Mars - about 0.006 atm. Due to the pressure of the atmosphere, a force of 10 N acts on each square centimeter of our body.
ATMOSPHERE PRESSURE
Air weight.
Most of us think that air is "nothing", but air is clearly "something" if it is made up of certain gases. Gas has no definite size or shape, but it occupies space
The earth's surface and all bodies on it experience the pressure of the air mass, i.e. experiencing atmospheric pressure. For 1 sq. cm. presses with a force of 1 kg 33g
Air weight
In 1643, Evangelista Torricelli showed that air has weight. Together with V. Viviani, Torricelli conducted the first experiment on measuring atmospheric pressure, inventing the Torricelli tube (the first mercury barometer), a glass tube in which there is no air. In such a tube, mercury rises to a height of about 760 mm.
BUT
B
D
FROM
Air has mass and this mass exerts pressure on the earth's surface and all objects on it.
Evangelista Torricelli
Torricelli found that the height of the mercury column in his experiment did not depend on the shape of the tube, nor on its inclination. At sea level, the height of the mercury column has always been about 760mm. The first mercury barometer was invented by Torricelli in 1643.
Normal atmospheric pressure at a temperature of 0° at sea level at a latitude of 45° is 760 mm Hg = 1310 hPa.
ATMOSPHERE PRESSURE
MERCURY BAROMETER Atmospheric pressure is the force with which air presses on the earth's surface.
In the XVII century, Robert Hooke proposed to improve the barometer
Using a mercury barometer is inconvenient and unsafe, so the aneroid barometer was invented "Aneroid" means without liquid
Early aeronauts found that it became difficult to breathe as they ascended. The same thing happens when climbing mountains. Why is this happening?
100 m
760 mm
0 m
200 m
750 mm
300 m
740 mm
730 mm
What pattern did you notice in the change in atmospheric pressure?
For every 100 m, the pressure changed by 10 mm Hg. st
Points on the map with the same atmospheric pressure connect lines - isobars
- Earth's atmosphere. Atmosphere pressure.
- History of the discovery of atmospheric pressure
- Evidence for the existence of atmospheric pressure
- The effect of atmospheric pressure on humans, use in the human body
- Atmospheric pressure is the pressure exerted by the atmosphere on all objects in it and the Earth's surface.
- For the first time, air was weighed by Galileo, before him it was believed that air was weightless.
- Calculate the force with which the air presses on the area of \u200b\u200bthe notebook opened in front of you. Atmospheric pressure is normal 101300 Pa.
- The surface area of the human body is about 15,000 cm2. Calculate the force with which the air presses on a person. Atmospheric pressure is taken equal to 101300 Pa.
- 10 cm of water was poured into a glass with a bottom area of 0.002 m2. Calculate the weight of the water and the bottom pressure. Compare this pressure with normal atmospheric pressure.
- I succeeded the most...
- I can commend myself for...
- I can praise my classmates for...
- I was surprised...
- It was a revelation for me that...
- In my opinion it didn't work...because...
- For the future, I will...
- If the Earth's atmosphere did not rotate along with the Earth around its axis, then the strongest hurricanes would arise on the Earth's surface.
- According to Pascal's calculations, the Earth's atmosphere weighs as much as a copper ball with a diameter of 10 km would weigh - five quadrillion (5000000000000000) tons!
- - on Earth, the temperature would be approximately -170 ° C, all water spaces would freeze, and the land would be covered with an ice crust.
- - there would be complete silence, since sound does not propagate in the void; the sky would become black, since the color of the firmament depends on the air; there would be no twilight, dawns, white nights.
- - the twinkling of the stars would stop, and the stars themselves would be visible not only at night, but also during the day (we do not see them during the day due to the scattering of sunlight by air particles).
- - Animals and plants would die.
