A device for determining wind direction. Test questions for the section
"Atmospheric pressure" - Standard pressure. Variability and influence on weather. Barometer. Aneroid barometer. Torricelli. Normal pressure. Pressure stage. Changes atmospheric pressure. Atmosphere pressure. Story. The gravity of the air column. Atmosphere. Reduction to sea level. Moon. What would happen on Earth if airy atmosphere suddenly disappeared.
"Air Movement" - Warm light air, goes upstairs. How does air move vertically in the center of a cyclone? What weather is associated with an anticyclone? The influence of neighboring territories on the climate of Russia. How does the circular movement of air occur in an anticyclone? Azores maximum. Showers, thunderstorms. Slow warming. An atmospheric vortex with low pressure in the center.
“Tornadoes and tornadoes” - Centrifugal forces drive heavy drops of water and hail to the periphery of the funnel. The shape of tornadoes can be varied - a column, a cone, a glass, a barrel, a whip-like rope. Houses and farms may be destroyed, people may die. Tornado - the strongest atmospheric vortex in the central part of the cyclone. Tornadoes have the shape of a rotating trunk, pipe or funnel hanging from the parent cloud.
“Atmospheric fronts” - An anticyclone is a vortex with high pressure in the center. Comparative characteristics cyclone and anticyclone. At the crest of a wave, a mass of warm air is surrounded by cold air. Storm. Winter location atmospheric fronts. Arctic AF. A cyclone is a vortex with low pressure at the center. Warm front. Antarctic VMs.
“Atmospheric pressure geography” - Tasks: Evangelista Torricelli. How much does air weigh? Equipment: Writing Verification work. From a height of 2000 m to 150 m of ascent - 10 mm Hg; 6000 m for 200 m of ascent – 10 mmHg. Where is 80% of the mass of air found? REPEATING PREVIOUSLY STUDYED MATERIAL (frontal survey). Summarizing. For 100 m of ascent, the pressure drops by 10 mm Hg.
“Lesson Wind” - Devices. Speed. Rose of Wind. Wind characteristics. Monsoon. When it whistles, there is a trembling in the river. “Married” - on the lake. A weather vane is a device for determining direction. Anemometer is a device for determining wind strength. It swoops down and bends the trees. Storm wind blows at a speed of 19-22 m/s. It prowls the field, sings and whistles, breaks trees, bends it to the ground.
There are 12 presentations in total
Movement atmospheric air occurs due to uneven heating earth's surface the sun. Due to this, a difference arises in the values of temperature and pressure in different parts of the earth’s surface, which determines the movements air masses both in horizontal and vertical directions (winds).
Local heating or cooling of land in any area globe accompanied by a corresponding decrease or increase in pressure, leading to the formation of relatively short-term but powerful air currents, the so-called cyclones and anticyclones. At the center of the cyclone, heated air rises to the upper layers of the atmosphere, where it cools and moves to the periphery. At the same time, colder layers of air are directed below from the periphery to the center, which move counterclockwise in a vortex-like manner due to the rotation of the earth around its axis. As a result of such circulation of atmospheric air, which covers vast areas of the earth's surface during its movement, the wind force in cyclones can reach large values and lead to catastrophic consequences. The weather usually becomes cloudy and accompanied by precipitation atmospheric precipitation. The opposite picture occurs during anticyclones, which are usually accompanied by dry and clear weather.
In addition to cyclones and anticyclones, there are various local winds. These include breezes - periodic winds formed as a result of temperature differences on land and water; they blow during the day from the sea to the land, and at night into reverse direction; mountain winds, the origin of which is explained by the uneven heating of mountain slopes and valleys, as a result of which rising air currents are formed during the day from bottom to top, and at night in the opposite direction; hairdryer - very dry and warm wind, formed in mountainous areas and destroying vegetation
Air movement is usually characterized by direction and speed. The direction is determined in bearings and is designated by the point on the horizon from which the wind blows (north-south, west, north-east, south-west, etc.). Speed is measured by the distance traveled by the wind per unit time (meters per second). The device with which the direction of the wind is determined is called a weather vane; An anemometer is used to determine the speed of air movement.
In hygienic practice important has a wind rose. Since each area is characterized by a known repeatability of the wind direction, it seems possible to designate this repeatability by constructing a special graph characterizing the most frequently encountered, i.e., predominant, direction. For this purpose, segments are laid out on the corresponding rhumb lines, the length of which indicates the number of repetitions of the wind direction as a percentage of total number all winds during the observation period (year, season, month). The ends of these segments are connected by straight lines, thus obtaining a graph characterizing the prevailing winds in a given area (Fig. 5). Hygienic value The wind rose lies in the fact that it makes it possible to obtain a visual representation of the prevailing winds in a given area and, in accordance with this, plan the construction of residential areas, children's institutions, hospitals, sanatoriums, etc. Rational placement them in relation to industrial enterprises protects these objects from negative influence winds bringing with them various atmospheric pollution(dust, smoke, harmful gases, etc.).
Rice. 5. Wind rose with a predominant north-west wind direction.
Air movement in the outdoor atmosphere is essential from a hygienic point of view. The role of winds lies primarily in the fact that due to the mixing of air masses, heat, cold and moisture are transferred from one area to another, which causes weather changes. Winds increase the evaporation of moisture from the surface water spaces, moistened soil, etc., and also promote ventilation populated areas and freeing the atmosphere from harmful impurities (self-purification air environment). The effect of air movement on the body is that it is both at high and low low temperatures in most cases it enhances heat transfer. But at high temperatures this increase in heat transfer improves well-being, and at low temperatures it plays negative role, promoting hypothermia, which can sharply reduce the body's resistance to colds. The role also seems unfavorable high speeds air movement in indoors(drafts). However, weak air currents (velocities up to 0.4-0.5 m/sec are considered acceptable) bring significant benefits, as they help maintain thermal comfort.
Technology, 3rd grade, Ragozina T.M., Grineva A.A. , Mylova I.B., 2012.
The textbook was developed in accordance with the requirements of the federal state educational standard for primary general education and the concept of the “Promising Primary School" In the first part of the textbook, students are presented in a visual form with a technology for processing natural, artificial and synthetic materials that is accessible to their age. Schoolchildren make and decorate their crafts necessary for lessons on the surrounding world, mathematics and literary reading. The second part of the textbook is devoted to the practice of working on a computer.
MODELING OF DECORATIVE PLATES.
Make one decorative plate out of clay for yourself, and another for decorative painting as a gift for a first grader.
Roll into a ball and flatten it to form a thin, even sheet.
To obtain a three-dimensional image, roll blank balls. Fashion the details from the blanks: head, arms, legs, hair, shirt (blouse), trousers (skirt), shoes.
CONTENT
TECHNOLOGY FOR MANUFACTURING PRODUCTS FROM VARIOUS MATERIALS
MODELING BIRDS FROM CLAY
MODELING DECORATIVE PLATES
DEVICE FROM PAPER STRIPES
CARDBOARD
MEASUREMENT FOR ANGLES
WRITING STAND
BOX WITH REMOVABLE LIVER
DEVICE FOR DETERMINING DIRECTION OF MOVEMENT WARM AIR.
TEXTILE MATERIALS
DOLLIES FOR FINGER THEATER
COLLAGE
SNAKE FOR DETERMINING THE DIRECTION OF WARM AIR MOVEMENT
GIFT PACKAGING
THREAD APPLICATION
DECORATIVE DESIGN OF PRODUCTS WITH EMBROIDERY
PALETTE
NEW YEAR'S TOYS
WIRE KEYCHAIN
POSTCARD-LANDSCAPE
BOOK REPAIR WITH COVER REPLACEMENT
CORRUGATED CARDBOARD GIFT CARDS
TOYS-SOUVENIRS FROM PLASTIC PACKAGING CAPSULES
DECORATIVE PANEL
CARDBOARD FIGURES WITH ELEMENTS OF MOTION FOR THE THEATER
WORKING WITH THE CONSTRUCTOR
PROJECT OF COLLECTIVE CREATION OF A PARK OF MACHINES
FOR CARGO TRANSPORTATION
COLLECTIVE MODEL CREATION PROJECT
AGRICULTURAL EQUIPMENT
MATERIALS AND TOOLS FOR LESSONS
GLOSSARY OF TERMS
PRACTICE USING A COMPUTER
TECHNICAL DEVICES FOR WORKING WITH INFORMATION
COMPUTER
RULES FOR SAFE WORK ON A COMPUTER
TECHNICAL DEVICES THAT CAN BE CONNECTED
TO THE COMPUTER
INFORMATION CARRIERS
WORKING WITH AN ELECTRONIC DISK
COMPUTER PROGRAMS
HOW TO WORK WITH A COMPUTER MOUSE
COMPUTER KEYBOARD
CONTROL TASKS
COMPUTER PROGRAM FOR CREATION AND DISPLAY OF PRESENTATIONS
MAIN MENU OF THE PROGRAM FOR CREATING AND DISPLAYING PRESENTATIONS
COMPUTER COLLECTIONS
WE WORK WITH THE PROGRAM FOR CREATING AND DISPLAYING PRESENTATIONS
GRAPHIC EDITOR
PAINT GRAPHIC EDITOR WINDOW
SAVING A DRAWING ON YOUR COMPUTER
WORKING WITH A GRAPHIC EDITOR
HOW TO TURN OFF YOUR COMPUTER
GLOSSARY OF TERMS.
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Air velocity can be measured in different places working space depending on the purposes of the study.
Anemometers are used to measure air speed various designs. The choice of anemometer type is determined by the measured air velocity.
Air velocity is measured various types anemometers: vane anemometers (flow speed from 0.3 to 0.5 m/s), cup and induction (speed within 1–30 m/s), hot-wire anemometers and catathermometers (speed no more than 0.5 m/s). Thermal anemometers allow you to measure minor fluctuations in air flow and temperature throughout the volume of a room. Anemometers are shown in Figure 2.4.
To measure intensity thermal radiation actinometers and radiometers are used.
A cup anemometer senses air movement with four hollow aluminum hemispheres, while a vane anemometer senses air movement through a wheel with plates that rotate under the pressure of the air flow. This movement is transmitted by a system of gear wheels to arrows moving along graduated dials, on which the countdown is made. Air velocity is measured as follows. Having written down initial position the arrow on dials (the arrows are not set to zero), on small dials only whole divisions are taken into account, the device is placed in the air stream. On the device there is: on the left a dial showing hundreds of divisions, on the right - thousands of divisions; A full revolution of the hand of the large dial gives 100 divisions. The anemometer must be placed in the air flow so that the axis of rotation of the wheel is parallel for a vane anemometer, and perpendicular to the direction of the air flow for a cup anemometer. After the cups or wings of the anemometer overcome the inertia of the device and acquire maximum speed, by turning the lever located on the side of the device, turn on the arrows, while simultaneously turning on the stopwatch to count the measurement time. After 1 minute, without removing the device from the test site, turn off the device’s arrows, while simultaneously noting the time of measurement (in seconds).
Conversion of the resulting number of revolutions in 1 s to the air flow speed in m/s is carried out using the graphs presented in Figures 2.5a and 2.5b, where the number of revolutions of 1 s is plotted along the vertical axis, and the air flow speed in m/s is plotted along the horizontal axis .
Rice. 2.5. Graphs for determining air speed using an anemometer:
a – cup; b – winged
Anemometers have high inertia and begin to work when air moves at a speed of about 0.5 m/s; the pressure created by an air flow of lower speed is not able to overcome the resistance of the axle of a wheel with wings or cups, therefore, catathermometers and hot-wire anemometers are used to measure low air speeds in rooms. To determine the total cooling capacity of the air environment, to measure low air speeds (up to 2 m/s), a device called a catathermometer is used.
The spherical catathermometer, shown in Figure 2.6, is an alcohol thermometer with two reservoirs - a spherical one at the bottom and a cylindrical one at the top with a division scale from 31 to 41 °C.
The amount of heat lost by the catathermometer when it is cooled from 38 to 35 °C is constant under all environmental conditions, and the duration of cooling is different and depends on the mutual action of all meteorological factors.
The amount of heat in millicalories lost from 1 cm 2 of the catathermometer reservoir is called its factor F, the value of which is indicated on the device.
Dividing the factor by the time (in seconds) during which the catathermometer cooled from a temperature of 38 to 36 °C, we obtain the cooling force of the air:
The speed of air movement is determined by formulas selected depending on the magnitude f/Δ t. Value Δ t is the difference between average temperature catathermometer (36.5 °C) and ambient temperature.
If , then (2.3)
If , then (2.4)
Determination of the total cooling force of the air using a catathermometer is carried out as follows. The device is immersed in water heated to 60–70 °C (but not more than 80 °C to avoid boiling of alcohol in the device and rupture of the tank), keep it in water until it is filled with alcohol to 1/3 or 1/4 of the volume of the upper expansion of the capillary. Then the catathermometer is removed from the water, thoroughly wiped and suspended at the measuring point. The device is cooled by ambient air. When the alcohol column reaches 38 °C, turn on the stopwatch and measure the cooling time of the device ( T, c) by 3° (from 38 °C to 35 °C). Next, calculations are made.
Air velocity less than 1 m/s is also measured by hot-wire anemometers. The operation of the hot-wire anemometer is based on the principle of cooling the sensor located in air flow and heated by electric current.
The sensor is a semiconductor microresistance. The device is powered either from a 220 V network or from small 1.5 V batteries.
A hot-wire anemometer measures air speeds from 0.03 to 5 m/s at temperatures from 1 to 60 °C. Using a hot-wire anemometer, you can also measure the room air temperature, for which the device is switched accordingly.
Study of barometric pressure in research meteorological conditions allows, on the one hand, to more fully take into account the dependence of temperature and relative humidity air from barometric pressure (as the pressure increases, the temperature rises), and on the other hand, this indicator has a significant influence on the characteristic endothermic (moisture evaporation) and exothermic (steam condensation) processes that have big influence for meteorological comfort.
Aneroid barometer (Fig. 2.7), designed for measuring atmospheric pressure in the range from 600–800 mm Hg. Art.
Rice. 2.7. Aneroid barometer:
1 – body; 2 – aneroid; 3 – glass; 4 – scale;
5 – metal plate; 6 – arrow; 7 – axis
main part barometer-aneroid - a light, elastic, hollow inside metal box (aneroid) 2 with a corrugated (wavy) surface. The air from the box has been pumped out. Its walls are stretched by a springy metal plate 5. Using special mechanism an arrow 6 is attached, which is mounted on an axis 7. The end of the arrow moves along a scale 4, marked in mm Hg. Art. All parts of the barometer are placed inside housing 1, covered at the front with glass 3.
The pressure value is determined as the algebraic sum of the scale reading and corrections, which are indicated in the device passport.
The intensity of thermal radiation is measured by actinometers of various designs, the action of which is based on the absorption of radiant energy and its conversion into thermal energy, the amount of which is recorded in various ways.
Ensuring the meteorological conditions and air purity required by the standards in the working and service areas of the premises is provided by ventilation, air conditioning and heating systems.
Ventilation is an organized and controlled air exchange that ensures the removal of polluted air from a room and the supply of fresh, clean air to the removed area.
Industrial ventilation is used for technical and sanitary purposes. For technical purposes, it is used in various technological processes; for sanitary and hygienic purposes, ventilation is used to create normal working conditions through proper air exchange in production premises. Air exchange is carried out by removing air from the room that does not meet the requirements of sanitary standards and supplying clean fresh air. In this process, the amount of air removed and supplied must be equal.
Based on the method of air movement, there are two main types of ventilation: natural and mechanical.
The choice of ventilation system depends on the characteristics production process, the type of building, the nature of the released hazards and the required air exchange rate.
Ventilation is called natural if air exchange is carried out by using natural air movement as a result of heat or wind pressure. Thermal pressure is created as a result of the presence of a temperature difference or difference specific gravity internal and external air, and wind - the movement of external air.
Natural ventilation is called aeration when natural air exchange is organized, i.e. carried out by regulating the inflow and exhaust, due to the opening of vents, wall valves, and lanterns.
In practice, there is also an unorganized method of natural ventilation (infiltration), i.e. when air exchange is carried out due to random holes and cracks in window and door openings, in the walls and ceilings of buildings and is possible in rooms where no more than a single air exchange per hour is necessary.
With mechanical ventilation, air exchange is achieved due to the pressure difference created by a fan driven by an electric motor. Mechanical ventilation is used in cases where the heat generation in the workshop is insufficient for the systematic use of aeration, and also if the amount or toxicity of harmful substances released into the room requires maintaining constant air exchange regardless of external meteorological conditions.
With mechanical ventilation, the air is almost always pre-treated. IN winter time The supply air is heated and cooled in the summer. If necessary, the air is humidified or dehumidified. If the air removed (supplied) by mechanical ventilation is dusty or contains large quantities harmful gases and vapors, it is subjected to purification.
Ventilation systems according to their purpose are divided into supply, exhaust and supply and exhaust ventilation, as well as working and emergency.
Depending on the place of application, ventilation is distinguished: general exchange, designed to exchange the air of the entire room, and local, providing the supply or exhaust of air directly at the workplace, i.e. at places of release of harmful substances.
In those rooms where a sudden influx of toxic or explosive substances is possible, emergency exhaust ventilation is installed, which is switched on automatically based on the readings of gas analyzers configured to the concentration of gases or vapors permissible according to sanitary and fire safety requirements.
Regardless of the presence of artificial ventilation in all rooms, it is also necessary to provide openings in the fences (windows, transoms) for ventilation.
Mechanical ventilation can be arranged in such a way that constant, predetermined conditions of temperature, humidity, air purity are maintained in the ventilated room, regardless of external conditions and regime fluctuations technological process. This type of ventilation is called air conditioning.
Typically, before entering the room, conditioned air undergoes heat and moisture treatment in units called air conditioners, which consist of air heating devices - air heaters, air cooling devices - surface or contact air coolers, and air drying devices.
The air in the heaters receives heat from the finned or smooth surfaces of the tubes through which the coolant flows - water or steam.
In surface air coolers, air transfers heat to the surfaces of the tubes through which it passes cold water or other coolant. In contact coolers, direct contact of cooled air with water occurs; usually the air passes through the rain space of the irrigation chamber, in which cooled water is sprayed with nozzles. Air dehumidification is carried out using moisture-absorbing substances: solid (silica), liquid (solutions of lithium chloride, calcium chloride).
Quantitatively, any method of air exchange can be characterized by the frequency of air exchange, i.e. a value showing how many times per unit of time (per minute, hour) occurs full shift the total volume of air in the room.
The safety requirements for the ventilation system are set out in SSBT GOST 12.4.021–75:
Fans of exhaust systems serving premises with production facilities of categories A and B must be made of materials that do not cause sparking;
The explosion and fire hazard of industrial premises should not be increased by the use of ventilation systems;
Ventilation systems serving premises with production facilities of categories A and B, where static electricity may occur, must ensure electrostatic safety and have grounding.
In rooms with permanent or long-term (more than 24 hours) stay of people, it is necessary to provide cold period year maintaining the required internal air temperatures by supplying heat with heating systems.
Building heating systems must satisfy following requirements, i.e. provide:
Uniform heating of the room air within heating season;
Safety against fire and explosions;
Possibility of regulation;
Linking with ventilation systems;
Sound pressure levels are within normal limits;
Lowest air pollution.
Heating systems are divided into local and central. In local heating systems, the heat generator (boiler), heat pipes (pipes) and heating devices (batteries) are combined and located in the heated room. IN central systems In heating, heat generation occurs in some center (in the boiler room), and the coolant is supplied to the heating devices located in the heated room through pipelines.
Depending on the type of coolant used, heating can be water, steam and air.
Water heating systems are divided into:
According to the principle of supplying coolant to heating devices - two-pipe and single-pipe;
On systems with natural motivation (circulation) and artificial motivation - using circulation pump;
For systems with top wiring and systems with bottom wiring.
Water heating is safer (relative to steam heating), because the temperature of heating devices does not exceed 80–90 °C.
Steam heating systems are divided into systems with top wiring and systems with bottom wiring. In steam heating systems, water vapor, condensing in heating devices, releases latent heat vaporization. This heat is transferred into the room through the walls of the heating device, and the condensate flows through the condensate line back into the boiler for reuse. Disadvantages of steam heating: heat heating devices, which can lead to the ignition of flammable substances and dust, and as a result, to burns of operating personnel.
Air heating systems can be heating systems, in which complete air recirculation is carried out, and heating and ventilation systems - used Fresh air. Air heating has the following advantages: hygiene, safety, rapid increase in room temperature, eliminating many local heating devices. It is advisable to use air heating for heating large industrial premises.
The basis for certification of workplaces for working conditions is the compliance of air parameters with the data given in tables 2.6, 2.7, 2.8 and 2.9, which characterize the class of working conditions in terms of microclimate indicators for industrial premises and open areas at different times of the year.