Purpose: to study the reasons for the formation of atmospheric pressure; find out the dependence of precipitation on atmospheric pressure; develop the ability to establish causal relationships between elements of the weather; education of ecological culture and respect for nature.
Equipment: a computer with a projector for showing a presentation, a visual aid on a disk, Internet resources, a climate map of the world, atlas maps.
Lesson type: combined
Lesson plan:
- Organizing time
- Knowledge update
- Learning new material
- Anchoring
- Lesson summary
During the classes
I. Organizational moment.
II. Knowledge update
III. Learning new material.
Introductory conversation.
Do you often listen to weather reports on TV or radio? What elements of the weather are often mentioned? (pressure, precipitation, temperature, wind speed, etc.)
Do you notice at what pressure it usually happens overcast weather, and it rains, but when is the weather clear and dry? (VD - clear weather; ND - cloudy, rain)
Problem. What needs to be learned to explain the planet's uneven rainfall? (to explain the uneven precipitation on the planet, you need to know how atmospheric pressure is distributed on it).
So, the topic of the lesson is "Distribution of areas of atmospheric pressure and precipitation at the surface of the Earth"
What questions we have to answer today:
- Does air have weight?
- What instruments and in what units is the pressure measured?
- How does atmospheric pressure change with altitude?
- How are the areas of atmospheric pressure distributed across the latitudes of the Earth?
- How does precipitation depend on atmospheric pressure?
1. The Earth's atmosphere is about 1 thousand kilometers thick, each of us is pressed by a column of air weighing 15 tons. Why don't we feel this pressure? (the pressure inside a person is equal to atmospheric, internal and external pressure are balanced).
2. To determine atmospheric pressure, special devices are used - barometers. The invention of the barometer belongs to the Italian mathematician, physicist Evangelist Torricelli.
3. Let's consider the principle of operation of a mercury barometer and aneroid barometer. Consider a drawing of a mercury barometer. What elements does it consist of?
A mercury barometer is a liquid barometer in which atmospheric pressure is measured by the height of a column of mercury in a tube sealed from above and lowered with its open end into a vessel with mercury. and Mercury barometers are the most accurate instruments, they are equipped with meteorological stations, they are used to check the operation of other types of barometers.
In everyday life, mechanical barometers ( Aneroid) <рисунок 1>... There is no liquid in the aneroid (Greek “aneroid” - “anhydrous”). It shows the atmospheric pressure acting on a corrugated thin-walled metal box in which a vacuum is created. When the atmospheric pressure decreases, the box expands slightly, and when it rises, it contracts and acts on the spring attached to it. These changes are transmitted to the arrow, which moves on a circular scale, divided by millimeters or millibars.
Atmosphere pressure measured in millimeters mercury column(mmHg) or millibars (MB).
Per normal pressure Atmospheric pressure is conventionally assumed to be 760 mm Hg, which is close to the average atmospheric pressure at sea level. Air pressure is more than 760 mm Hg. considered increased, less - decreased.
Assignment to the class. How will the atmospheric pressure change with the rise in the mountains? (pressure decreases with height by an average of 1 mm for every 10.5 m rise). Define:
- the average atmospheric pressure on the shore of Lake Baikal, if its height above sea level is about 500 m. (710 mm Hg)
- the average atmospheric pressure for the city of Moscow, if it lies at an altitude of 120 m above sea level. (748 mm Hg)
4. How is the distribution of areas of atmospheric pressure across latitudes. It depends on the temperature.
What happens to air when it heats up? (Expands and becomes light)
Where will the heated air go? (up)
This process is called upward air movement.
By analogy, explain how the downward movement of air occurs.
If atmospheric pressure is dependent on temperature, explain from the chalkboard drawing how the areas of atmospheric pressure are distributed across the globe.<рисунок 2>... Sketch in a notebook and distribute the pressure areas.
Globally, on the globe, how many pressure belts can be identified? (three with a predominance of low and four - with a predominance high pressure)
How does atmospheric pressure change in temperate latitudes Northern hemisphere in winter and summer? (In winter - rises above the continents (winter highs), the region low pressure persists only over the oceans (Icelandic and Aleutian minima))
5.
With VD - clear weather; ND - cloudy, rain. Using this relationship, mark wet and dry latitudes in your drawings.
Anchoring.
- 25 ° -30 ° N and _____ and at the poles ______ air currents -> ______ -> _______.
- At ______ and 65 ° N and y.sh. _______ air currents -> _______ -> _______.
- Determine in which pressure belt are located: Oslo, North Pole, Ulan-Ude, Beijing.
Lesson summary.
What are the reasons for the formation of different atmospheric pressure? (distribution solar heat and the rotation of the Earth).
How are atmospheric pressure and precipitation interrelated?
History
Variability and influence on the weather
On the the earth's surface atmospheric pressure varies from place to place and over time. Particularly important are the non-periodic changes in atmospheric pressure that determine the weather, associated with the emergence, development and destruction of slowly moving areas of high pressure (anticyclones) and relatively rapidly moving huge eddies (cyclones), in which reduced pressure prevails. Fluctuations in atmospheric pressure at sea level within 641 - 816 mmHg Art. (inside the tornado, the pressure drops and can reach 560 mm Hg).
Atmospheric pressure decreases with increasing altitude, since it is created only by the overlying layer of the atmosphere. The dependence of pressure on altitude is described by the so-called. barometric formula.
see also
Notes (edit)
Links
Wikimedia Foundation. 2010.
See what "Atmospheric pressure" is in other dictionaries:
ATMOSPHERIC pressure, the pressure of the atmosphere of air on the objects in it and on the earth's surface. At each point in the atmosphere, atmospheric pressure is equal to the weight of the overlying column of air; decreases with height. Average atmospheric pressure for ... ... Modern encyclopedia
Atmosphere pressure- ATMOSPHERIC PRESSURE, the pressure of the air atmosphere on the objects in it and on the earth's surface. At each point in the atmosphere, atmospheric pressure is equal to the weight of the overlying column of air; decreases with height. Average atmospheric pressure for ... ... Illustrated Encyclopedic Dictionary
The pressure exerted by the atmosphere on all objects in it I on the earth's surface. It is determined at each point of the atmosphere by the mass of the overlying column of air with a base equal to one. Above sea level at a temperature of 0 ° C at a latitude of 45 ° ... ... Ecological Dictionary
- (Atmospheric pressure) the force with which air presses on the earth's surface and on the surface of all bodies in it. AD at this level is equal to the weight of the overlying air column; at sea level, on average, about 10 334 kg per 1 m2. AD not ... ... Marine dictionary
Pressure atmospheric air on the objects in it and on the earth's surface. At each point in the atmosphere, atmospheric pressure is equal to the weight of the overlying column of air; decreases with height. The average atmospheric pressure at sea level is equivalent to ... Big Encyclopedic Dictionary
Atmosphere pressure- The absolute pressure of the near-earth atmosphere. [GOST 26883 86] atmospheric pressure Ndp. barometric pressure day pressure The absolute pressure of the near-earth atmosphere. [GOST 8.271 77] Inadmissible, non-recommended barometric pressure ... ... Technical translator's guide
Atmosphere pressure- the pressure of atmospheric air on the objects in it and on the earth's surface. At each point in the atmosphere, the air flow is equal to the weight of the overlying column of air; decreases with height. Average arterial pressure at sea level is equivalent to Hg pressure. Art. in height ... ... Russian encyclopedia of labor protection
Atmosphere pressure- The pressure exerted by the weight of the atmosphere on the earth's surface. Syn .: air pressure ... Geography Dictionary
The hydrostatic pressure exerted by the atmosphere on all objects in it. At each point, it is determined by the weight of the overlying air column and decreases with height: at an altitude of 5 km, for example, it is half of the normal value, for which ... ... Encyclopedia of technology
The force, with a swarm of air surrounding the earth on all sides, presses on its surface and on all bodies on this surface. A. d. Varies depending on the position of a given point in relation to sea level: the higher the point is above ... ... Technical Railway Dictionary
Atmosphere pressure- is the absolute pressure of the near-earth atmosphere. [GOST 26883 86, GOST 8.271 77] Term heading: General terms Encyclopedia headings: Abrasive equipment, Abrasives, Highways, Automotive equipment ... Encyclopedia of terms, definitions and explanations building materials
Section 31. Atmospheric pressure
Remember from the course of natural history what is called atmospheric pressure.
The concept of atmospheric pressure. The air is invisible and light. However, it, like any substance, has mass and weight. Therefore, it exerts pressure on the earth's surface and on all bodies on it. This pressure is determined by the weight of a column of air as high as the entire atmosphere - from the earth's surface to its uppermost boundary. It has been established that such a column of air presses on every 1 cm 2 of the surface with a force of 1 kg 33 g (respectively, per 1 m 2 - More than 10 tons!) So, Atmosphere pressure- This is the force with which the air presses on the earth's surface and on all objects on it.
The surface of the human body is on average 1.5 m 2. According to the air, press on it with a weight of 15 tons. Such pressure is capable of crushing all living things. Why don't we feel it? This is due to the fact that inside the human body there is also pressure - internal, and it is equal to atmospheric. If this balance is disturbed, the person feels bad.
Measurement of atmospheric pressure. Atmospheric pressure is measured using a special device - a barometer. Translated from Greek, this word means "Gravity Meter".
Weather stations use mercury barometer... Its main part is a glass tube 1 m long, sealed at one end. Mercury, a heavy liquid metal, is poured into it. The open end of the tube is immersed in a wide bowl, also filled with mercury. When turned over, the mercury from the tube poured out only to a certain level and stopped. Why did it stop and not pour out all? Because the air puts pressure on the mercury in the bowl and does not release all of it from the tube. If the atmospheric pressure decreases, then the mercury in the tube goes down and vice versa. The height of the column of mercury in the tube on which the scale is applied determines the value of atmospheric pressure in millimeters.
At a parallel of 45 0 at sea level at an air temperature of 0 0 C under air pressure, a column of mercury rises in the tube to a height of 760 mm. This air pressure is considered normal atmospheric pressure... If the column of mercury in the tube rises above 760 mm, then the pressure elevated, Below - lowered... Consequently, the pressure of a column of air throughout the atmosphere is balanced by the weight of a column of mercury with a height of 760 mm.
On hikes and expeditions, they use a more convenient device - aneroid barometer... "Aneroid" in translation from Greek means "bezridinny": there is no mercury in it. Its main part is an elastic metal box, from which air was downloaded. This makes it very sensitive to changes in external pressure. At elevated pressures, it contracts, while decreasing, it expands. These vibrations are transmitted through a special mechanism to the arrow, which indicates on the scale the value of atmospheric pressure in millimeters of mercury.
The dependence of pressure on the height of the area and air temperature. Atmospheric pressure depends on the height of the terrain. The higher the sea level, the lower the air pressure. It decreases, since with the rise, the height of the air column decreases, which presses on the earth's surface. In addition, with altitude, the pressure also decreases because the density of the air itself decreases. At an altitude of 5 km, atmospheric pressure is half the normal pressure at sea level. In the troposphere, ascending every 100 m, the pressure decreases by about 10 mm Hg. Art.
Knowing how the pressure changes, you can calculate both the absolute and the relative height of the place. There is also a special barometer - altimeter, In which, along with the scale of atmospheric pressure, there is also a scale of heights. So, each area will have its own normal pressure: at sea level - 760 mm Hg. century, in the mountains, depending on the height - lower. For example, for Kiev, which lies at an altitude of 140-200 m above sea level, an average pressure of 746 mm Hg will be normal. Art.
Atmospheric pressure also depends on the air temperature. When heated, the volume of air increases, it becomes less dense and light. For this, the atmospheric pressure also decreases. On cooling, the opposite occurs. Consequently, with a change in air temperature, pressure also changes continuously. During the day, it rises twice (in the morning and in the evening) and decreases twice (in the afternoon and after midnight). In winter, when the air is cold and heavy, the pressure is higher than in summer when it is warmer and lighter. So, weather changes can be predicted behind the pressure change. A decrease in pressure indicates precipitation, an increase in dry weather. Changes in atmospheric pressure also affect the well-being of people.
Distribution of atmospheric pressure on Earth. Atmospheric pressure, like air temperature, is distributed on the Earth in stripes: they distinguish between low and high pressure belts. Their formation is associated with heating and air movement.
The air warms up well above the equator. From this it expands, becomes less dense, and therefore lighter. Lighter than air rises up - occurs upward movement air. Therefore, there, at the surface of the Earth, the course of the year is establishedbeltlow pressure ... Above the poles, where temperatures are low throughout the year, the air cools and becomes denser and heavier. So it goes down - happens downward movement air - and the pressure increases. Therefore, at the poles formedbeltshigh pressure ... The air that rises above the equator spreads to the poles. But, before reaching them, at altitude it cools down, becomes heavier and falls on parallels 30-35 0 in both hemispheres. As a result, there are formedhigh pressure belts ... In temperate latitudes, at parallels 60-65 0 of both hemispheres,low pressure belts .
Thus, there is a close dependence of atmospheric pressure on the distribution of heat and air temperatures on the Earth, when the ascending and descending air movements cause uneven heating of the earth's surface.
Questions and tasks
1. Determine how much the air in the classroom weighs if it is 8 m long, 6 m wide, 3 m high.
2. Why does atmospheric pressure decrease with altitude?
3. Why does the pressure change in the same place? How does this change in air temperature affect?
4. Determine the approximate relative height of the mountain top if the barometer shows 720 mm at the foot of the mountain, and 420 mm at the top.
5. How is atmospheric pressure distributed on Earth?
6. Remember what absolute height your area. Calculate which atmospheric pressure can be considered normal for your area.
They even mention atmospheric pressure in weather forecasts, but what is its nature? What determines low and high atmospheric pressure? How does its change affect human health?
What it is?
Back in 1638, people had little idea that such a phenomenon, in general, existed, until the Duke of Tuscany decided to decorate Florence with fountains on high altitude... His attempt failed miserably, since the water did not rise above ten meters. Then the time came for the first experiments in this area.
With the development of science, it became clear that pressure is a physical quantity that reports the amount of force applied perpendicularly to a unit area of any surface. The atmosphere is no exception. It presses on our planet with the help of air, which is present everywhere.
The mass of the air around us is millions of times less than that of the earth, but this is quite enough for all objects and creatures to experience its influence on themselves. Every day about fifteen tons of air presses on us, but we cannot feel this, because the internal pressure human body the same as atmospheric.
Low and high atmospheric pressure
Like any physical quantity, the pressure can be measured. IN The international system units are used for this pascal (Pa), in Russia, bars and millimeters of mercury are also used.
The average value is taken at a temperature of zero degrees at sea level at a latitude of 45 degrees. It is designated as normal atmospheric pressure and is 760 millimeters of mercury or 101325 pascals.
What does atmospheric pressure depend on? First of all, it depends on the amount of air per unit area: the less it is, the lower the pressure and vice versa. It directly depends on the height. At high altitudes, the air is more rarefied, so its indicator decreases with rising. At an altitude of 5 km, its strength is only two times less, at an altitude of 20 km - about 18 times.
Pressure tends to change in different time days and seasons. An important factor is the temperature. At night, when the temperature drops, the pressure is slightly lower than during the day. On the continents, high atmospheric pressure is observed in winter, and low in summer.
Pressure zoning
Areas Globe warmed up unevenly, as a result, the pressure distribution occurs zonal. In some places, the air heats up and decreases its pressure. Rising up and gradually cooling, it moves to neighboring areas, increasing the pressure there.
This redistribution air masses well seen in equatorial belt where because of high temperatures pressure is always low, and in neighboring tropical zones it is usually elevated. In Antarctica and the North Pole, constant high pressure is a consequence of the influx of air from temperate latitudes.
As mentioned above, the pressure is inherent in seasonal fluctuations, but these changes are not too significant. In general, pressure indicators are stable: there are always zones of high and low pressure on the planet.
Influence of high atmospheric pressure
A person can feel the power of this phenomenon on himself, climbing the mountains. Many people are familiar with the ear popping when you overcome the sometimes insignificant rises. You can feel it by diving deep under the water, by the way, maximum depth such a dive without special equipment is no more than 170 meters (although this is quite risky).
IN Everyday life the person also feels pressure changes, especially if there are sudden changes. High atmospheric pressure is accompanied by clear weather and dryness harmful substances feel sharper in the air. As a result, allergies and respiratory problems are aggravated.
The increase in pressure is clearly reflected in the well-being of hypertensive patients. By helping to reduce the number of leukocytes in the blood, it can weaken the immune system. Therefore, during periods of high blood pressure, it is more difficult for a person to fight infections and other diseases.
Air pressure- the force with which the air presses on the earth's surface. Measured in millimeters of mercury, millibars. On average, it is 1.033 g per 1 cm. Sq.
The reason for the formation of wind is the difference in atmospheric pressure. The wind blows from an area of higher atmospheric pressure to an area with a lower one. How more difference at atmospheric pressure, the stronger wind... The distribution of atmospheric pressure on Earth determines the direction of the winds prevailing in the troposphere at different latitudes.
Formed during the condensation of water vapor in the rising air due to its cooling.
... Water in a liquid or solid state that falls on the earth's surface is called precipitation.
By origin, two types of precipitation are distinguished:
falling out of clouds (rain, snow, groats, hail);
formed at the surface of the Earth (, dew, frost).
Precipitation is measured by a layer of water (in mm), which is formed if the precipitated water does not flow down and does not evaporate. On average, 1130 mm falls to the Earth per year. precipitation.
Precipitation distribution. Precipitation distributed over the earth's surface very unevenly. Some territories suffer from excess moisture, others from lack of moisture. The territories located along the northern and southern tropics, where the air is high and the demand for precipitation is especially great, receive especially little precipitation.
The main reason for this unevenness is the placement of atmospheric pressure belts. So, in the equatorial region in the low-pressure belt, constantly heated air contains a lot of moisture, it rises up, cools and becomes saturated. Therefore, in the area of the equator, many clouds form, and there are heavy rains. There is a lot of precipitation in other areas of the earth's surface, where there is low pressure.
Downward pressure prevails in high pressure belts. air currents... Cold air, sinking, contains little moisture. When lowered, it shrinks and heats up, due to which it moves away from the saturation point, becomes drier. Therefore, in the areas high blood pressure there is little rainfall over the tropics and at the poles.
By the amount of precipitation it is still impossible to judge the provision of the territory with moisture. Possible evaporation - volatility must be taken into account. It depends on the amount of solar heat: the more of it, the more moisture can evaporate, if there is any. The volatility can be large and the volatility small. For example, evaporation (how much moisture can evaporate at a given temperature) is 4500 mm / year, and evaporation (how much actually evaporates) is only 100 mm / year. The moisture content of the territory is judged by the ratio of evaporation and evaporation. The moisture coefficient is used to determine the moisture content. Humidification factor - ratio annual quantity precipitation to evaporation for the same period of time. It is expressed as a percentage. If the coefficient is 1, the moisture is sufficient, if less than 1, the moisture is insufficient, and if it is greater than 1, then the moisture is excessive. According to the degree of moisture, humid (humid) and dry (arid) areas are distinguished.
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