A device for detecting the movement of warm air. Air movement
7.2. Instruments for determining the direction and speed of air movement
Weathervane Wilde (Figure 19) . This device is intended for use at meteorological stations for the purpose of long-term continuous observations in different regions for wind directions and speeds. It should be taken into account that the data recorded at meteorological stations located in different areas must be comparable. This condition presupposes the use of only commercially produced weather vanes that have a strictly uniform design.
Rice. 19. Weathervane Wilde |
The design of a serial weather vane is shown in the figure. As can be seen from the figure, the direction of air flow is determined using a weather vane - a wedge-shaped plate with a counterweight. The wind direction is fixed using a coupling with rigidly fixed rods (pins) - pointer indicators. When the wind vane rotates, the board for determining the wind speed always takes a position perpendicular to the direction of the wind, and under the pressure of the latter, it deviates from the vertical position to one or another angle. Based on the position of the board's deflection, using graduated pointer pins, the wind speed is determined. The device contains two boards: a light one (200 g) for measuring speeds not exceeding 20 m/s and a heavy one (800 g) for speeds up to 40 m/s. The approximate wind speed can be determined by multiplying the pin size by 2 (if using a light board) or 4 (if using a heavy board). The weather vane for observations is installed in an open place on a pole 8–10 m high. The pin with the letter C (N) should be set to the north along the compass or the noon line, that is, along the meridian of the given place. Based on long-term observations, patterns of directions and speeds of air flows are derived, which make up the features of climate and weather conditions in a particular area. These reference data are widely used for various purposes, some of the above, including in hygienic practice, in particular when there is a need for hygienic control over the planning and development of populated areas. |
Anemometers. In sanitary and hygienic practice, portable anemometers are most widely used - cup anemometer And vane anemometer(Figure 20). The receiving part of the cup anemometer is a pinwheel made of 4 hollow hemispheres (cups), mounted on a metal axis, the lower end of which is connected to a counting mechanism (tachometer). The arrows on the dial of the device show the number of revolutions of the hemispheres around the axis: the large one - the number of units and tens, and the two small ones - the number of hundreds and thousands. To turn the revolution counter on and off, there is a lever and two rings on the device box. If there is a need to measure air movement at any height, the device can be mounted on a pole using a screw at the bottom. In this case, to remotely turn the meter on and off, a cord is rigidly fixed to the switch lever and passed through the rings. By marking the ends of the cord, you can turn the meter on and off.
The procedure for measuring air (wind) speed. Record the readings of all hands (on small dials only whole divisions are taken into account). The device is mounted on a pole or held in outstretched arms, depending on the specific tasks. In this case, the device must be in a strictly vertical position. Next, wait 1 - 2 minutes until the turntable rotates completely, after which the device counter and stopwatch are turned on simultaneously with a cord or directly with the handles. |
Observation is carried out for 10 minutes. After this exposure, turn on the counter and stopwatch and record the readings of the counter hands again. Then the difference between the two meter readings is calculated, divided by the observation time, expressed in seconds, and the number of revolutions per second is obtained.Rice. 20. Cup anemometers ( A) And ) |
winged (
The cup anemometer is used to determine average wind speeds in the range of 1.0 – 2.0 m/s. Using this device, you can make not only meteorological observations in the open atmosphere, but also determine the speed of air flow in ventilation systems, in particular, for the purpose of hygienic assessment of the effectiveness of ventilation in rooms and devices for various purposes.
Vane anemometer The principle of operation is identical to the previous device. However, this device has some design features, increasing its sensitivity and lower limits for determining the speed of air flow. The receiving part in a vane anemometer is a mill (impeller) made of light metal blades mounted on a horizontal axis connected to the revolution counter.
During operation, the device is oriented along the flow so that the counting mechanism is behind the flow relative to the impeller. To overcome the inertia of the device resistance, it is enough for the impeller to rotate at idle for only 0.5 minutes. The duration of observation is limited to 2 minutes. The procedure for calculating air flow speed is the same as for a cup anemometer. Using a vane anemometer, it is possible to measure air flow speeds from 0.3 to 5.0 m/s.
An example of determining the air speed of a cup anemometer. On an open work site, in order to study the working conditions of construction workers, one of the wind speed studies was carried out among the numerous regular observations planned by the program. We take the initial readings of the device counter. At the same time, the hand indicating thousands was located between numbers 3 and 4 of the corresponding dial. That is, in this case we write down the number of whole thousands - 3. The arrow showing hundreds was located between the numbers of the corresponding dial 5 and 6. We write down the next number after number 3, indicating the number of whole hundreds - 5. The large hand showed 76 divisions. Following the previous two digits, we write down the number 76, indicating the number of individual revolutions of the device axis. Thus, the initial value on the counter was 3576.
Next, the wind speed was determined for 10 minutes while the instrument's counter and stopwatch were turned on. After the specified time, the counter and stopwatch were turned off. Using the above method, we take new readings from the device, which amounted to 6123. observation time in seconds – 1060 = 600 s. Thus, in 600 seconds the axis of the device made 6123 revolutions. To determine the number of revolutions in 1 s, divide the difference in the counter readings by 600: (6123 – 3576): 600 = 2547: 600 = 4.245 rpm. If the research does not require extreme accuracy of the research, which is the case in most cases, then the found value is taken as the air speed in m/s. That is, the speed of air movement in in this example was equal to 4.245 m/s. If, however, there is a need for a very accurate study, then convert according to the graph or table attached to the device, rpm. m/s.
Catathermometer. This device is a special alcohol thermometer with a scale of 35-38°C or 33-40°C. The catathermometer was originally designed to measure the cooling effect of air temperature on the human body. Subsequently, it was shown that the catathermometer does not produce heat loss from the surface of human skin and does not take into account the influence of thermal radiation, which has a significant effect on the body’s heat exchange. Currently, it is used almost exclusively for measuring low air speeds, although, using a catathermometer, it is possible to roughly determine which of its readings, under various conditions of production activity, coincides with the optimal well-being of people, and to evaluate the cooling ability of meteorological factors (temperature and air speed).
Rice. 21. Ball catathermometers (Rice. 20. ) and cylindrical (Hill catathermometer) () And ) |
Depending on the design, catathermometers are cylindrical (Hill catathermometer) or spherical (Figure 21); they are a thermometer in which the upper end of the capillary tube has an expansion, which is partially filled with alcohol when heated. The principle of both catathermometers is that the rate of decrease in the temperature of the devices depends, in addition to the air temperature, on the speed of its movement. When working with a cylindrical catathermometer, the time of temperature decrease from 38 to 35°C is measured, with a ball one - from 38 to 35°C, 39 to 34°C, 40 to 38°C. Moreover, it is easy to notice that the average value of the indicated temperature differences is always equal to 36.5°C, that is, the average human temperature. This made it possible, during the initial purpose of the devices, to simulate to some extent the cooling effect of air on the human body (“cooling ability of air”). During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank. This value (catafactor) is a constant (constant value) of the device and is indicated on each catathermometer in the form of its constant factor, expressed in µcal/cm 2 . |
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.
Procedure for working with catathermometers. Before measurement, the catathermometer is immersed in water at a temperature of 65–80°C and held until the alcohol fills at least half of the capillary expansion. After this, the catathermometer is thoroughly wiped, hung on a tripod at the measurement point, and the cooling time is set using a stopwatch in the above temperature ranges. It is very important that the catathermometer is stationary during the observation period, otherwise additional air movement will be simulated.
Rice. 20. Measurements at one point are repeated several times, the first result is discarded, and the average value of the cooling value is derived from subsequent ones (
N During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.). The cooling value using a cylindrical catathermometer is calculated using the formula: During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank. F
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.– catafactor, μcal/cm2;
– the number of seconds during which the alcohol column dropped from 38 to 35°C.
When working with a ball catathermometer, if observations are carried out in the temperature range of 38-35С, calculation of the value 1 –When working with a ball catathermometer, if observations are carried out in the temperature range of 38-35С, calculation of the value produced according to the same formula as for a cylindrical catathermometer. When observing in other intervals for calculation
Rice. 20.– the number of seconds during which the alcohol column dropped in the corresponding temperature intervals. from 38 to 35С.
By the amount of cooling ( During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.) and the air temperature during the study period, the air speed is calculated using the formulas:
for air speed< 1 м/с (до 0,6)
for air speed > 1 m/s (> 0.6)
In the given formulas the following symbols are used:
V– desired air speed, m/s;
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.– the amount of cooling of the dry catathermometer, μcal;
Q– difference between average temperature body (36.5С) and ambient air temperature,С;
0.20 and 0.40; 0.13 and 0.47 are empirical coefficients.
An example of determining air speed using a ball catathermometer. The researcher determined the speed of air movement in classroom No. 2 of the Department of Hygiene of the State Educational Institution of Higher Professional Education "VSMU Roszdrav" using a ball catathermometer at an air temperature during the observation period of 20°C. catafactor ( Procedure for working with catathermometers.) device – 573 µcal/cm 2 . The first result of measuring the time the temperature of the device dropped from 40 to 33°C, as mentioned above, was discarded. The next three measurements showed respectively a time of 210, 221 and 205 seconds. When calculating the average time, the result is: (210 + 221 + 205) : 3 = 636: 3 = 212 s.
mkal.
We find the value that will be equal to:
Air speed in the classroom< 1 м/с, так как H/Q< 0,6. Подставляем найденные величины в соответствующую, указанную выше формулу, и рассчитываем скорость движения воздуха:
For accelerated and approximate calculations of air speed, you can use special tables (Tables 10 and 11). If the research was carried out under the conditions presented in the previous example, where the value H/ Q was equal to 0.38, then at the intersection of the horizontal line corresponding to the indicated value with the column corresponding to 20°C, we find the result from the table - 0.239 m/s.
Table 10
Instruments for determining the direction and speed of air movement
Weathervane Wilde(Figure 19) . This device is intended for use at meteorological stations for the purpose of long-term continuous observations in different regions of wind directions and speeds. It should be taken into account that the data recorded at meteorological stations located in different areas must be comparable. This condition presupposes the use of only commercially produced weather vanes that have a strictly uniform design.
Rice. 19. Weather vane Vilde | The design of a serial weather vane is shown in the figure. As can be seen from the figure, the direction of air flow is determined using a weather vane - a wedge-shaped plate with a counterweight. The wind direction is fixed using a coupling with rigidly fixed rods (pins) - pointer indicators. |
Anemometers. When the wind vane rotates, the board for determining the wind speed always takes a position perpendicular to the direction of the wind, and under the pressure of the latter, it deviates from the vertical position to one or another angle. Based on the position of the board's deflection, using graduated pointer pins, the wind speed is determined. The device contains two boards: a light one (200 g) for measuring speeds not exceeding 20 m/s and a heavy one (800 g) for speeds up to 40 m/s. The approximate wind speed can be determined by multiplying the pin size by 2 (if using a light board) or 4 (if using a heavy board). The weather vane for observations is installed in an open place on a pole 8–10 m high. The pin with the letter C (N) should be set to the north along the compass or the noon line, that is, along the meridian of the given place. Based on long-term observations, patterns of directions and speeds of air flows are derived, which make up the features of climate and weather conditions in a particular area. These reference data are widely used for various purposes, some of the above, including in hygienic practice, in particular when there is a need for hygienic control over the planning and development of populated areas. In sanitary and hygienic practice, portable anemometers are most widely used - vane anemometer cup anemometer
The procedure for measuring air (wind) speed. Record the readings of all hands (on small dials only whole divisions are taken into account). The device is mounted on a pole or held in outstretched arms, depending on the specific tasks. In this case, the device must be in a strictly vertical position. Next, wait 1 - 2 minutes until the turntable rotates completely, after which the device counter and stopwatch are turned on simultaneously with a cord or directly with the handles. | Observation is carried out for 10 minutes. After this exposure, turn on the counter and stopwatch and record the readings of the counter hands again. Then the difference between the two meter readings is calculated, divided by the observation time, expressed in seconds, and the number of revolutions per second is obtained. Rice. 20. Rice. 20. Cup anemometers ( ) And) |
) and winged (
This value approximately corresponds to the desired air flow speed. To obtain a more accurate value, use a table or graph for converting the number of revolutions into speed. A table or graph is included with the instrument.
Vane anemometer The cup anemometer is used to determine average wind speeds in the range of 1.0 – 2.0 m/s. Using this device, you can make not only meteorological observations in the open atmosphere, but also determine the speed of air flow in ventilation systems, in particular, for the purpose of hygienic assessment of the effectiveness of ventilation in rooms and devices for various purposes.
The principle of operation is identical to the previous device. However, this device has some design features that increase its sensitivity and lower limits for determining the speed of air flow. The receiving part in a vane anemometer is a mill (impeller) made of light metal blades mounted on a horizontal axis connected to the revolution counter.
During operation, the device is oriented along the flow so that the counting mechanism is behind the flow relative to the impeller. To overcome the inertia of the device resistance, it is enough for the impeller to rotate at idle for only 0.5 minutes. The duration of observation is limited to 2 minutes. The procedure for calculating air flow speed is the same as for a cup anemometer. Using a vane anemometer, it is possible to measure air flow speeds from 0.3 to 5.0 m/s. On an open work site, in order to study the working conditions of construction workers, one of the wind speed studies was carried out among the numerous regular observations planned by the program. We take the initial readings of the device counter. At the same time, the hand indicating thousands was located between numbers 3 and 4 of the corresponding dial. That is, in this case we write down the number of whole thousands - 3. The arrow showing hundreds was located between the numbers of the corresponding dial 5 and 6. We write down the next number after number 3, indicating the number of whole hundreds - 5. The large hand showed 76 divisions. Following the previous two digits, we write down the number 76, indicating the number of individual revolutions of the device axis. Thus, the initial value on the counter was 3576.
Next, the wind speed was determined for 10 minutes while the instrument's counter and stopwatch were turned on. After the specified time, the counter and stopwatch were turned off. Using the above method, we take new readings from the device, which amounted to 6123. observation time in seconds – 10´60 = 600 s. Thus, in 600 seconds the axis of the device made 6123 revolutions. To determine the number of revolutions in 1 s, divide the difference in the counter readings by 600: (6123 – 3576): 600 = 2547: 600 = 4.245 rpm. If the research does not require extreme accuracy of the research, which is the case in most cases, then the found value is taken as the air speed in m/s. That is, the air speed in this example was equal to 4.245 m/s. If, however, there is a need for a very accurate study, then convert according to the graph or table attached to the device, rpm. m/s.
Catathermometer. This device is a special alcohol thermometer with a scale of 35-38°C or 33-40°C. The catathermometer was originally designed to measure the cooling effect of air temperature on the human body. Subsequently, it was shown that the catathermometer does not produce heat loss from the surface of human skin and does not take into account the influence of thermal radiation, which has a significant effect on the body’s heat exchange. Currently, it is used almost exclusively for measuring low air speeds, although, using a catathermometer, it is possible to roughly determine which of its readings, under various conditions of production activity, coincides with the optimal well-being of people, and to evaluate the cooling ability of meteorological factors (temperature and air speed).
Rice. 21. Ball catathermometers ( Rice. 20.) and cylindrical (Hill catathermometer) ( ) And) | Depending on the design, catathermometers are cylindrical (Hill catathermometer) or spherical (Figure 21); they are a thermometer in which the upper end of the capillary tube has an expansion, which is partially filled with alcohol when heated. The principle of both catathermometers is that the rate of decrease in the temperature of the devices depends, in addition to the air temperature, on the speed of its movement. When working with a cylindrical catathermometer, the time of temperature decrease from 38 to 35°C is measured, with a ball one - from 38 to 35°C, 39 to 34°C, 40 to 38°C. Moreover, it is easy to notice that the average value of the indicated temperature differences is always equal to 36.5 ° C, that is, the average human temperature. This made it possible, during the initial purpose of the devices, to simulate to some extent the cooling effect of air on the human body (“cooling ability of air”). During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank. This value (catafactor) is a constant (constant value) of the device and is indicated on each catathermometer in the form of its constant factor, expressed in µcal/cm 2 . Moreover, it is easy to notice that the average value of the indicated temperature differences is always equal to 36.5°C, that is, the average human temperature. Before measurement, the catathermometer is immersed in water at a temperature of 65–80°C and held until the alcohol fills at least half of the capillary expansion. After this, the catathermometer is thoroughly wiped, hung on a tripod at the measurement point, and the cooling time is set using a stopwatch in the above temperature ranges. It is very important that the catathermometer is stationary during the observation period, otherwise additional air movement will be simulated. Measurements at one point are repeated several times, the first result is discarded, and the average value of the cooling value is derived from subsequent ones ( During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.). The cooling value using a cylindrical catathermometer is calculated using the formula: |
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.
Procedure for working with catathermometers.– catafactor, μcal/cm2;
Rice. 20.– the number of seconds during which the alcohol column dropped from 38 to 35°C.
When working with a ball catathermometer, if observations are made in the temperature range of 38-35°C, calculate the value During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank. produced according to the same formula as for a cylindrical catathermometer. When observing in other intervals for calculation During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank. use the formula:
where (7)
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.– required cooling value, mcal;
– constant, μcal/cm 2 ´deg.);
When working with a ball catathermometer, if observations are carried out in the temperature range of 38-35С, calculation of the value 1 – When working with a ball catathermometer, if observations are carried out in the temperature range of 38-35С, calculation of the value 2 – temperature ranges in °C (40-33 or 39-34);
Rice. 20.– the number of seconds during which the alcohol column dropped in the corresponding temperature intervals. from 38 to 35°C.
By the amount of cooling ( During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.) and the air temperature during the study period, the air speed is calculated using the formulas:
for air speed< 1 м/с ( до 0,6)
(8)
for air speed > 1 m/s ( > 0.6)
(9)
In the given formulas the following symbols are used:
V– desired air speed, m/s;
During the cooling process, a constant amount of heat is lost from 1 cm 2 of the surface of the catathermometer tank.– the amount of cooling of the dry catathermometer, μcal;
Q– the difference between the average body temperature (36.5°C) and the ambient air temperature, °C;
0.20 and 0.40; 0.13 and 0.47 are empirical coefficients.
An example of determining air speed using a ball catathermometer. The researcher determined the speed of air movement in classroom No. 2 of the Department of Hygiene of the State Educational Institution of Higher Professional Education "VSMU Roszdrav" using a ball catathermometer at an air temperature during the observation period of 20°C. catafactor ( Procedure for working with catathermometers.) device – 573 µcal/cm 2 . The first result of measuring the time the temperature of the device dropped from 40 to 33°C, as mentioned above, was discarded. The next three measurements showed respectively a time of 210, 221 and 205 seconds. When calculating the average time, the result is: (210 + 221 + 205) : 3 = 636: 3 = 212 s.
mkal.
We find the value that will be equal to:
Air speed in the classroom< 1 м/с, так как H/Q < 0,6. Подставляем найденные величины в соответствующую, указанную выше формулу, и рассчитываем скорость движения воздуха:
For accelerated and approximate calculations of air speed, you can use special tables (Tables 10 and 11). If the research was carried out under the conditions presented in the previous example, where the value H/Q was equal to 0.38, then at the intersection of the horizontal line corresponding to the indicated value with the column corresponding to 20°C, we find the result from the table - 0.239 m/s.
The wind can create and destroy, it can help, and it can also destroy. Winds blow continuously on Earth. In this lesson we will learn why the wind blows, how to determine the strength of the wind, its direction using a weather vane and an anemometer. What is the role of wind in life and economic activity person, what types of winds exist.
Topic: Inanimate nature
The movement of warm and cold air on Earth is continuous.
Rice. 2. Scheme of formation of constant winds ()
Wind is a natural phenomenon, but such air movement can be observed even indoors. If you open the door of a room and bring a lit candle to the opening, its flame will deviate towards the corridor. This experiment proves that the warm air of the room has risen up and goes out into the corridor, displaced by the cold air that was below. Therefore, if a candle is placed on the floor, the candle flame will deviate towards the room, indicating the direction of movement of cold air.
Rice. 3. Experience in determining the direction of the wind indoors ()
During the day, land heats up faster and more strongly than water. But it also cools down faster. Therefore, the temperature over the sea and land is different: during the day the air is warmer over the land, and at night it is warmer over the sea.
Therefore during the day cold air from the sea moves to land (this wind is called the daytime breeze), and at night the wind blows in the opposite direction - from land to sea (this is the night breeze).
Rice. 4. A - Day breeze, B - Night breeze ()
The greater the temperature difference in various areas globe, the faster the air masses move, the stronger the wind blows. For life safety and ease of housekeeping, it is important for a person to know the direction of the wind. If the wind blows from the Arctic zone, it brings cold, and if it blows from the equatorial zone, it brings warmth.
There is a special device with which the direction of the wind is determined - vane.
At meteorological stations, the direction of the wind is monitored using a weather vane, which is installed at a height of 10 m. It consists of a light metal plate that rotates around its axis in a certain direction, indicating the direction of the wind. The wind gets its name from the side of the world from which it blows: from the north - northern, from the south - southern.
Rice. 6. Determination of wind direction ()
There is also a special device to determine the wind force - anemometer: the stronger the wind blows, the faster the turntable spins.
There is wind different strengths: weak, moderate, strong.
Rice. 8. Determination of wind force ()
If the wind is weak, then only the leaves sway on the trees.
The moderate wind also sways the branches of the trees.
A strong wind bends trees, tears off branches and tops.
This is a natural phenomenon, but it helps people a lot. The wind drives the clouds over the ground, and in different places rain, snow and hail fall. The wind carries polluted air away from cities and brings Fresh air from fields, forests and meadows. It dries roads, inflates the sails of ships, rotates the wings of windmills, and spreads seeds and pollen.
Rice. 14. The wind carries plant seeds ()
Rice. 15. Snow brought by the wind ()
Rice. 16. Waves raised by the wind ()
Rice. 17. Sails filled with wind ()
Man has long learned to use wind energy: windmill is an example of converting wind energy into mechanical energy. But now human economic and household activities are closely connected with electricity, therefore, to obtain electrical energy A wind generator was created from wind energy. Wind energy is a renewable form of energy, as it is a consequence of the activity of the Sun. Wind energy is a rapidly growing industry.
Rice. 19. Structure of a wind generator ()
But sometimes the wind reaches enormous power, it's called a hurricane. Such a wind breaks trees, blows off roofs of houses, breaks wires, and raises high waves. A strong wind at sea is called a storm.
Tornado or tornado - extremely strong atmospheric vortex, where the wind turns around an axis in a spiral. It takes the form of a column with a diameter of tens to several hundred meters and lasts from several minutes to several hours.
Most often (several dozen cases per year) tornadoes are observed in Tornado Alley in the United States - in a strip from northern Texas to Iowa. Here the temperature difference between cold and warm is most significant. air masses. In Russia, tornadoes are more often observed in the European part, especially in the central zone and in the south, but no more than 1-2 times in several years. A series of tornadoes in August 2002 in the Novorossiysk region caused the death of about 60 people and caused significant property damage.
It's a strong wind from big amount snow masses, accompanied by poor visibility on roads and any other terrain.
Wind from high temperature and low relative air humidity in steppes, semi-deserts and deserts.
So, the wind can both create and destroy.
In the next lesson we will remember what properties of air we already know from previous lessons. Let's consider a series of experiments that will introduce us to new properties of air: its volume, weight and elasticity. We will also find out where people use their knowledge about the properties of air in everyday life.
- Vakhrushev A.A., Danilov D.D. The world around us 3. M.: Ballas.
- Dmitrieva N.Ya., Kazakov A.N. The world around us 3. M.: Fedorov Publishing House.
- Pleshakov A.A. The world around us 3. M.: Education.
- Academician ().
- Festival of Pedagogical Ideas " Public lesson» ().
- Methodological circle ().
- Make a test (4 questions with three answer options) on the topic “Wind”.
- Prepare a report about tornadoes in our country.
- Conduct experiments to prove the movement of warm and cold air. Describe your actions, observations, results.
- *Write a fairy tale or a fantasy story on the theme “A warm wind caught me.”
2. Hygiene air environment in the practice of physical education and sports classes
Target: analysis of the properties of the air environment as factors determining human physical performance.
Tasks:
- list the physical properties of air that are important in the practice of sports and physical culture;
- clarify their hygienic standards;
- determine the influence of each factor on the state of the body and its physical performance;
- master the structure and principle of operation of instruments that determine the corresponding property of air (thermometer, psychrometer, anemometer, etc.);
- master the methodology, determine the actual state of air parameters at the time of the study;
- compare with standards, draw a conclusion about the impact of the above factors on a person’s condition and his performance;
- make recommendations for correcting classes physical culture and sports under similar air parameters.
Required: mercury and alcohol thermometers, thermograph, stationary and aspiration psychrometers, hygrometers, hygrograph, cup and vane anemometer, aneroid barometer, barograph.
Procedure for completing the task: get acquainted with theoretical provisions on the topic, get an assignment, master the device, principle operation of the device, the methodology for determining the indicator, make the necessary measurements and calculations, compare the result with the standard, draw a conclusion.
Theoretical justification of the topic. The physical properties of air have significant influence on the temperature homeostasis of the body, its psychostatus, on the functional activity of organs and systems and, ultimately, on human performance.
Temperature, humidity and air movement actively affect the body's heat metabolism, which is regulated by the central nervous system. Thermal interaction of the body with the external environment changes the tone of blood vessels and muscles. Low parameters of external environmental factors (at increased air speed) stimulate heat formation in the body (contractile and non-contractile thermogenesis), increasing energy consumption to maintain body temperature within normal limits.
When the air environment indicators are higher than those recommended for sports activities with minimal air mobility, the body stimulates heat transfer, the degree of which is determined by the state of the air (its humidity, temperature, speed of movement). This activates evaporation, convection or radiation of thermal energy from the body.
With prolonged exposure to negative environmental influences (cold damp air, hot damp air and other options), thermoregulation may fail, the development of pathological conditions, hypothermia (freezing), overheating (thermal, sunstroke) requiring emergency assistance.
Therefore, when changing microclimatic factors it is necessary to modify the volume and intensity of muscle efforts, since the adaptive capabilities of the body experience a certain tension, even stress.
2.1.1. Air temperature determination
Required: thermometers, tripods, stopwatch.
To measure air temperature and dynamically record it, mercury and alcohol thermometers, as well as thermographs, are used. Alcohol instruments are capable of measuring air temperature down to -130 °C. In this case, the following rules must be observed:
- do not hold the device in your hands, fix it in a special tripod, at a distance of at least 20 cm from the wall;
- record the indicator value after 10 minutes;
- devices should not be placed near heat sources (including humans);
- measurements are carried out in horizontal and vertical planes, with horizontal temperature fluctuations within 2-3 °C, and vertical temperature fluctuations of 2.5 °C per 1 m height;
- measurement is made at a height of 0.1; 0.5 and 1.5 m from the floor and diagonally across the room (opposite corners and middle).
The assessment is based on the difference in readings.
In the Tula region for residential and educational premises optimal temperature air should be considered 20-22 °C, for sports - 14-20 °C, depending on the type of activity (Table 19).
2.1.2. Determination of air humidity
Required: psychrometers, stopwatch, distilled water.
Humidity is the content of water vapor in the air, which has elasticity. Affects human performance by changing the body’s heat balance:(less than 30%) leads to loss of fluid and minerals through the skin and mucous membranes, and high (more than 60%) leads to excessive sweating (to prevent overheating), but low sweat evaporation. Consequently, such conditions complicate a person’s muscular activity, create additional stress on the body’s adaptive systems, reduce performance and, therefore, require a reduction in the volume and intensity of physical activity.
Types of air humidity: maximum, absolute, relative, physiological saturation deficiency.
In sports practice, relative humidity is more often used. To determine it, there is special equipment: a hygrometer, a hygrograph (the operation of these devices is based on changes in the length of a dried tuft of hair at different humidity levels), stationary and aspiration psychrometers (the determination is made by the difference in readings of mercury thermometers, one of which records the temperature of dry air, the other - humidified air). ). The measurement is carried out at three points in the hall (diagonally). Device operating time: 4 min. summer time
and 15 minutes - in winter. Method for measuring air humidity. On the fabric of one of the thermometers in aspiration psychrometer Apply 1-2 drops of distilled water from a special pipette 4 minutes in summer and 15 minutes in winter before the test. The device is fixed at a height of 2 m from the floor surface (soil). Start the fan, sucking air through the device. Readings are taken from both thermometers after 4 minutes in summer and 15 minutes in winter from the start of fan operation. Using a special table, find the relative humidity value and compare it with
standard indicators , draw a conclusion about the influence of a specific temperature and humidity on the state of the body, give recommendations on optimizing the magnitude and intensity of physical activity in specific environmental conditions. The standard value of air humidity varies significantly (30-60%) depending on the person’s condition (rest, stress) and microclimatic conditions. At rest in ordinary clothes at t° = 18-20 ° C and weak air movement, the optimal level for a person is 40-60%.
relative humidity
Required;
For a person’s performance, not only temperature and humidity are of certain importance, but also the speed and direction of air movement, which affect both the temperature balance of the body and its psychological state (strong flows in speed (more than 6-7 m/s) irritate , weak - calm), on the frequency and depth of breathing, pulse rate, on the speed of a person’s movement.
It has been established that the optimal values of air speed during sports activities are 0.3-0.5 m/s in most indoor sports facilities (in a swimming pool - 0.2 m/s), 1-4 m/s (light wind) - in sports facilities open type; in the locker room, shower - 0.15 m/s;
in residential premises - 0.1-0.3 m/s. If the air speed is more than 2 m/s, the result will not be counted during athletics competitions if the wind is tailwind.
To determine the speed of movement, there is special equipment: hand-held vane and cup anemometers (for open objects) and a catathermometer (for closed ones).
The direction of movement of the air flow at the time of the study can be determined by the weather vane, by the direction of the smoke stream, by the movement of branches and leaves (Table 20). In sports hygiene the concept " Rose of Wind ", i.e. a graphic representation of the prevailing winds in a given area. The wind rose helps to correctly orient sports objects
in relation to factories, plants, major highways to create an environmentally friendly air environment in the area of the open sports facility. The sports facility should be located on the windward side in relation to industrial facilities and major highways.
Then it is necessary to compare the value of the indicator with the normative one, indicate the influence of the factor on the state of the body during physical education and sports, and make recommendations for adjusting the load to optimize the body’s performance.
2.1.4. Determination of atmospheric pressure
Required: barometer, calculator.
The normal atmospheric pressure is 760 mmHg. Art. at an air temperature of 0 ° C, at sea level and a latitude of 45 °. Under these conditions, the atmosphere presses on 1 cm of the Earth's surface with a force of 1033. Daily pressure fluctuations at the Earth's surface are 4-5 mm, and annual fluctuations are 20-30 mm Hg. Art. These fluctuations are felt by weather-sensitive people, which is a sign of weakening protective forces body.
Atmospheric pressure of 1 millibar corresponds to the pressure of a body weighing 1 g on a surface of 1 cm: 1 mb = 0.7501 mm Hg. Art.
Low (reduced) barometric pressure affects a person working in conditions of medium mountains (more than 2000 m above sea level) and, especially, high mountains (more than 3000 m). Under these conditions, the partial pressure of oxygen in the atmosphere decreases, conditions of relative hypoxia are created, limiting motor activity person. Adaptation of the body can last from 7-10 days to a month, depending on the altitude above sea level and the functional state of human organs and systems. During this period, physical performance is reduced, which implies a conscious reduction in the volume and intensity of the athlete’s physical activity.
With a sharp climb to the mountains (alpine skiing), a weakened person (overtraining, post- or pre-illness state, violation of the regime, etc.) develops mountain (high-altitude) illness, in which the main pathogenetic symptom is brain hypoxia and tissue hypoxia (shortness of breath, changes in blood pressure , heart rate, weakness up to loss of consciousness).
A sharp increase in atmospheric pressure can also be unfavorable for humans ( underwater species sports and work). It is known that for every 10 m of immersion, the pressure increases by 1 atmosphere. At the same time, due to the significant difference between external and internal (in the cavity organs) pressure, rupture of organs and large vessels is possible. These are the consequences of decompression sickness.
In sports practice, low atmospheric pressure is used as a factor in stimulating physical performance in aerobic sports activities.
Method of determination atmospheric pressure. The indicator is determined using an aneroid barometer, which records changes in atmospheric pressure through the deformation of the walls of a metal aneroid box. The values of the indicator can be expressed in mm Hg. Art., atmospheres, pascals, bars.
To convert from one unit of measurement to another, there are correction factors:
1 hPa = 1 g/cm = 0.75 mm Hg. Art.
The obtained value is compared with the standard value, a conclusion is drawn about the influence of the indicator on the human condition, and recommendations are given for adjusting the volume and intensity of muscle load.
Using a barometer, you can also determine the height of the area above sea level when climbing mountains. To do this, record the readings of the device before lifting and at the required height (sports or tourist base).
Each altitude corresponds to a certain atmospheric pressure. On average, for every 10.5 m of height, the pressure decreases by 1 mmHg. Art. In the absence of a barometer, the height of the area above sea level can be determined using a highly sensitive thermometer. It is necessary to measure the temperature of boiling water and use the table to clarify the corresponding height of the area (Table 21). 2.2. Study of the body's reactions to the complex effects of microclimatic factors
Target:
: determine the degree of adaptation of the body to specific microclimate conditions.
Tasks
- determine the microclimate parameters of the classroom (temperature, humidity, air movement, barometric pressure);
- assess the microclimate using the method of subjective heat sensations;
- measure skin temperature (forehead, back) using an electric thermometer at rest and after a standard load (15-second run in place at maximum pace or 3-minute (2-minute for women) run in place at a pace of 180 steps per minute);
Required- determine the nature of adaptation processes by the duration of the recovery period and the degree of change in skin temperature;
- draw a conclusion about the body’s resistance to the effects of microclimatic conditions at rest and during muscular activity.: research protocol, stopwatch, electric thermometer, barometer, thermometer, psychrometer, anemometer, calculator.
The human body is a highly organized self-regulating system capable of adapting to constantly changing weather and environmental conditions. At the same time, weakened people suffering from chronic diseases are sensitive to sudden changes in weather conditions in 30-70% of cases. They may appear lung symptoms ailments, in rare cases - disturbances in cardiac and brain activity.
During hygienic assessment external environment it is necessary to take into account the nature of physiological reactions that occur in the body under the influence of a complex of microclimatic and meteorological factors. Such reactions can be studied using various methods(determination of body temperature, changes in heart rate, blood pressure, gas exchange data and others). In hygienic sports practice, the following methods are used to study the influence of microclimate conditions on the state of the body: assessment of thermal sensation (subjective method), determination of skin temperature, cold test (objective methods).
2.2.1. Determining the speed and direction of air movement
The method for assessing thermal sensations consists of questioning the subject in accordance with a scale of subjective sensations: cold (1 point), cool (2 points), comfortable (3 points), warm (4 points), hot (5 points). It is important to determine the dynamics of these sensations in specific environmental conditions before, in the middle and at the end of the lesson. The most optimal feeling for a person is thermal comfort.
A healthy, seasoned person adapts relatively easily to small changes in the microclimate. At the same time, the significant subjectivity of this method requires support with data from objective assessment methods.
2.2.2. Method for determining skin temperature Fluctuations in microclimatic factors affect the tone and lumen of blood vessels, thereby changing skin temperature. The highest and relatively constant temperature
skin of the forehead and chest (approximately 31-34 ° C). The limbs are the main heat exchangers of the body; their temperature ranges from 27-30 °C.
To determine skin temperature, an electric thermometer is used, the sensor of which takes measurements at symmetrical points: - on the forehead (3-4 cm from);
midline
- on the chest (at the level of the 4th intercostal space);
- on the shoulder (middle of the outer surface);
Then the subject is given a standard load (3-minute running in place at a pace of 180 steps per minute) and the skin temperature is measured again at the same points. Temperature dynamics indicate the degree of adaptation to the load. If adaptation to stress is inadequate, skin temperature can drop significantly (by 2.5-3 °C).
2.2.3. Sweating study
In hot microclimates and physical work The intensity of thermoregulation can be determined by the intensity of sweating. Evaporation of 1 ml of sweat corresponds to the loss of 560 cal of heat by the body. Moreover, the higher the ambient temperature, the more intense the sweating. In order to assess the intensity of thermoregulatory processes, Minor's starch iodine method is used to determine the intensity of sweating.
An area of skin (forehead, back) is powdered with starch. The subject performs a physical load: a 15-second run in place at a maximum pace or a 3-minute run in place at a pace of 180 steps per minute (for women - 2 minutes). Then filter paper treated with the mixture is applied to these areas castor oil, 10% iodine tincture and ethyl alcohol. When wet, the paper turns dark blue due to the reaction of iodine with starch.
In a comfortable microclimate, uniform small colored dots are formed; with heavy sweating, large spots are formed, which indicates the tension of thermoregulation.
A comprehensive study of microclimate conditions in the gym. Microclimate indicators are recorded before and after the training session. This allows us to identify changes in these indicators in the dynamics of the lesson and, on this basis, develop recommendations for optimizing sanitary and hygienic conditions in a particular room.
2.3. Test questions for the section
Each altitude corresponds to a certain atmospheric pressure. On average, for every 10.5 m of height, the pressure decreases by 1 mmHg. Art. In the absence of a barometer, the height of the area above sea level can be determined using a highly sensitive thermometer. It is necessary to measure the temperature of boiling water and use the table to clarify the corresponding height of the area (Table 21).: control of knowledge within the specified topic, including that completed during independent study.
Scroll test questions:
- the importance of the air environment in human life;
- hygienic assessment air temperatures in sports practice, standardization;
- hygienic assessment of air humidity in physical education practice, standardization;
- hygienic assessment of the speed and direction of air movement, standardization;
- the hygienic role of atmospheric pressure in the practice of physical education and sports;
- hygienic assessment solar radiation, radioactivity of the air;
- chemical composition air, hygienic assessment in physical education practice, standardization;
- air pollution (mechanical, microbial), its prevention in indoor sports facilities, connection with the morbidity of those involved;
- concept of weather, climate, acclimatization;
- study of the body's reactions to the complex effects of microclimatic factors.
2.4. Literature by section
1. Volynskaya E.V. Hygienic basics of health: Toolkit. - Lipetsk: Publishing house LGPI, 2000. - P.10-26.
2. Laptev A.P. Hygiene of mass sports. - M.: FiS, 1984. - P.131-136.
3. Laptev A.P., Malysheva I.N. Hygiene workshop. - M.: FiS, 1987.
4. Laptev A.P., Polievsky S.A. Hygiene: Textbook for physical institutes. cult. - M.: FiS, 1990. - P.41-61.
5. Minkh A.A. General hygiene. - M.: Medicine, 1984. - P.18-76.
6. Polievsky S.A. Physical education student youth. - M.: Medicine, 1989. - P.87-89.