Lecture notes for the course “Aviation Meteorology. Aviation meteorology Meteorology for pilots

Atmosphere

Composition and properties of air.

The atmosphere is a mixture of gases, water vapor and aerosols (dust, condensation products). The share of the main gases is: nitrogen 78%, oxygen 21%, argon 0.93%, carbon dioxide 0.03%, others account for less than 0.01%.

Air is characterized by the following parameters: pressure, temperature and humidity.

International standard atmosphere.

Temperature gradient.

The air is heated by the ground, and density decreases with height. The combination of these two factors creates a normal situation where air is warmer at the surface and gradually cools with height.

Humidity.

Relative humidity is measured as a percentage as the ratio of the actual amount of water vapor in the air to the maximum possible at a given temperature. Warm air can dissolve more water vapor than cold air. If the air cools down, then it relative humidity approaches 100% and clouds begin to form.

Cold air in winter is closer to saturation. Therefore, winter has a lower cloud base and distribution.

Water can be in three forms: solid, liquid, gas. Water has a high heat capacity. In the solid state it has a lower density than in the liquid state. As a result, it softens the climate on a planetary scale. In a gaseous state it is lighter than air. The weight of water vapor is 5/8 of the weight of dry air. As a result, moist air rises above dry air.

Atmospheric movement

Wind.

Wind arises from a pressure imbalance, usually in the horizontal plane. This imbalance appears due to differences in air temperatures in neighboring areas or vertical air circulation in different areas. The root cause is solar heating of the surface.

Wind is named by the direction from which it blows. For example: northern blows from the north, mountain blows from the mountains, valley blows into the mountains.

Coriolis effect.

The Coriolis effect is very important to understand global processes in the atmosphere. The result of this effect is that all objects moving in the northern hemisphere tend to turn to the right, and in the southern hemisphere - to the left. The Coriolis effect is strong at the poles and disappears at the equator. The Coriolis effect is caused by the rotation of the Earth under moving objects. This is not some real force, it is an illusion of right rotation for all freely moving bodies. Rice. 32

Air masses.

An air mass is air that has the same temperature and humidity over an area of ​​at least 1600 km. An air mass can be cold if it formed in the polar regions, warm - from tropical zone. It can be marine or continental in humidity.

When a CVM arrives, the ground layer of air is heated by the ground, increasing instability. When the TBM arrives, the surface layer of air cools, descends and forms an inversion, increasing stability.

Cold and warm front.

A front is the boundary between warm and cold air masses. If cold air moves forward, it is a cold front. If warm air moves forward, it is a warm front. Sometimes air masses move until they are stopped by increased pressure in front of them. In this case, the frontal boundary is called a stationary front.

Rice. 33 cold front warm front

Front of occlusion.

Clouds

Types of clouds.

There are only three main types of clouds. These are stratus, cumulus and cirrus i.e. stratus (St), cumulus (Cu) and cirrus (Ci).

stratus cumulus cirrus Fig. 35

Classification of clouds by height:

Rice. 36

Lesser known clouds:

Haze - Forms when warm, moist air moves ashore, or when the ground radiates heat into a cold, moist layer at night.

Cloud cap - forms above the peak when dynamic updrafts occur. Fig.37

Flag-shaped clouds - form behind mountain peaks when strong wind. Sometimes it consists of snow. Fig.38

Rotor clouds - can form on the leeward side of the mountain, behind the ridge in strong winds and have the form of long ropes located along the mountain. They form on the ascending sides of the rotor and are destroyed on the descending ones. Indicates severe turbulence. Fig. 39

Wave or lenticular clouds - are formed by wave movement of air during strong winds. They do not move relative to the ground. Fig.40

Rice. 37 Fig. 38 Fig.39

Ribbed clouds are very similar to ripples on water. Formed when one air layer moves over another at a speed sufficient to form waves. They move with the wind. Fig.41

Pileus - when a thundercloud develops to an inversion layer. A thundercloud can break through the inversion layer. Rice. 42

Rice. 40 Fig. 41 Fig. 42

Cloud formation.

Clouds consist of countless microscopic particles of water of various sizes: from 0.001 cm in saturated air to 0.025 with ongoing condensation. The main way clouds form in the atmosphere is by cooling moist air. This occurs when the air cools as it rises.

Fog forms in cooling air from contact with the ground.

Updrafts.

There are three main reasons why updrafts occur. These are flows due to the movement of fronts, dynamic and thermal.

front dynamic thermal

The rate of rise of the frontal flow directly depends on the speed of the front and is usually 0.2-2 m/s. In a dynamic flow, the rate of rise depends on the strength of the wind and the steepness of the slope, and can reach up to 30 m/s. Thermal flow occurs when rising more than warm air, which in sunny days heats up from earth's surface. The lifting speed reaches 15 m/s, but usually it is 1-5 m/s.

Dew point and cloud height.

The saturation temperature is called the dew point. Let’s assume that the rising air cools in a certain way, for example, 1 0 C/100 m. But the dew point drops only by 0.2 0 C/100 m. Thus, the dew point and the temperature of the rising air approach 0.8 0 C/100 m. When they equalize, clouds will form. Meteorologists use dry and wet bulb thermometers to measure ground and saturation temperatures. From these measurements you can calculate the cloud base. For example: the air temperature at the surface is 31 0 C, the dew point is 15 0 C. Dividing the difference by 0.8 we get a base equal to 2000 m.

Life of the clouds.

During their development, clouds go through the stages of origin, growth and decay. One isolated cumulus cloud lives for about half an hour from the moment the first signs of condensation appear until it disintegrates into an amorphous mass. However, often the clouds do not break up as quickly. This occurs when the air humidity at the level of the clouds and the humidity of the cloud coincide. The mixing process is in progress. In fact, ongoing thermality results in a gradual or rapid spread of cloud cover over the entire sky. This is called overdevelopment or OD in the pilot's lexicon.

Continued thermality can also fuel individual clouds, increasing their lifetime by more than 0.5 hours. In fact, thunderstorms are long-lived clouds formed by thermal currents.

Precipitation.

For precipitation to occur, two conditions are necessary: ​​continuous updrafts and high humidity. Water droplets or ice crystals begin to grow in the cloud. When they get big, they start to fall. Snowing, rain or hail.

MINISTRY OF HIGHER AND SECONDARY SPECIAL EDUCATION OF THE REPUBLIC OF UZBEKISTAN

TASHKENT STATE AVIATION INSTITUTE

Department: "Air Traffic Control"

Lecture notes

at the rate " Aviation meteorology »

TASHKENT - 2005

"Aviation meteorology"

Tashkent, TGAI, 2005.

The lecture notes include basic information about meteorology, atmosphere, winds, clouds, precipitation, synoptic weather maps, baric topography maps and radar conditions. Describes movement and transformation air masses, as well as pressure systems. The issues of movement and evolution are considered atmospheric fronts, occlusion fronts, anticyclones, snowstorms, types and forms of icing, thunderstorms, lightning, atmospheric turbulence and regular service - METAR, international aviation code TAF.

Lecture notes were discussed and approved at a meeting of the Air Traffic Control Department

The method was approved by the FGA council at a meeting

Lecture No. 1

1. The subject and significance of meteorology:

2. Atmosphere, composition of the atmosphere.

3. The structure of the atmosphere.

Meteorology is the science of the actual state of the atmosphere and the phenomena occurring in it.

Under the weather commonly understood physical state atmosphere at any moment or period of time. Weather is characterized by a combination of meteorological elements and phenomena, such as Atmosphere pressure, wind, humidity, air temperature, visibility, precipitation, clouds, icing, ice, fog, thunderstorms, snowstorms, dust storms, tornadoes, various optical phenomena(halo, crowns).

Climate – long-term weather regime: characteristic of a given place, developing under the influence solar radiation, the nature of the underlying surface, atmospheric circulation, changes in the earth and atmosphere.

Aviation meteorology studies meteorological elements and atmospheric processes from the point of view of their influence on aviation technology and aviation activities, and also develops methods and forms of meteorological support for flights. Correct consideration of meteorological conditions in each specific case to best ensure the safety, economy and efficiency of flights depends on the pilot and dispatcher, on their ability to use meteorological information.

Flight and dispatch personnel must know:

What exactly is the influence of individual meteorological elements and weather phenomena on the operation of aviation;

Have a good understanding of physics atmospheric processes, creating various conditions weather and their changes in time and space;

Know the methods of operational meteorological support of flights.

Organization of aircraft flights civil aviation GA to scale globe, and meteorological support for these flights is unthinkable without international cooperation. There are international organizations that regulate the organization of flights and their meteorological support. This is ICAO ( International organization civil aviation) and WMO (World Meteorological Organization), which closely cooperate with each other on all issues of collection and dissemination of meteorological information for the benefit of civil aviation. Cooperation between these organizations is governed by special working agreements concluded between them. ICAO determines the meteorological information requirements arising from GA requests, and WMO determines the scientifically sound possibilities for meeting them and develops recommendations and regulations, as well as various guidance materials, mandatory for all its member countries.

Atmosphere.

Atmosphere is the air envelope of the earth, consisting of a mixture of gases and colloidal impurities ( dust, drops, crystals).

The earth is like the bottom of a huge air ocean, and everything living and growing on it owes its existence to the atmosphere. It delivers the oxygen necessary for breathing, protects us from deadly cosmic rays and ultraviolet radiation. solar radiation, and also protects the earth's surface from strong heating during the day and strong cooling at night.

In the absence of an atmosphere, the surface temperature of the globe would reach 110° or more during the day, and at night it would sharply drop to 100° below zero. There would be complete silence everywhere, since sound cannot travel in emptiness, day and night would change instantly, and the sky would be completely black.

The atmosphere is transparent, but it constantly reminds us of itself: rain and snow, thunderstorm and blizzard, hurricane and calm, heat and frost - all this is a manifestation of atmospheric processes occurring under the influence solar energy and during the interaction of the atmosphere with the surface of the earth itself.

Composition of the atmosphere.

Up to an altitude of 94-100 km. the percentage composition of the air remains constant - the homosphere (“homo” from Greek is the same); nitrogen – 78.09%, oxygen – 20.95%, argon – 0.93%. In addition, there is a variable amount of other gases in the atmosphere ( carbon dioxide, water vapor, ozone), solid and liquid aerosol impurities (dust, industrial gases, smoke, etc.).

The structure of the atmosphere.

Data from direct and indirect observations show that the atmosphere has a layered structure. Depending on what physical property atmosphere (temperature distribution, air composition at altitudes, electrical characteristics) is the basis for division into layers, there are a number of schemes for the structure of the atmosphere.

The most common scheme for the structure of the atmosphere is a scheme based on the vertical temperature distribution. According to this scheme, the atmosphere is divided into five main spheres or layers: the troposphere, stratosphere, mesosphere, thermosphere and exosphere.

3. What functions are assigned to the Glavhydromet of the Republic of Uzbekistan?

4. Characterize the composition of the atmosphere.

Lecture No. 2.

1. The structure of the atmosphere (continued).

2. Standard atmosphere.

Troposphere – the lower part of the atmosphere to an average altitude of 11 km, where 4/5 of the total mass is concentrated atmospheric air and almost all water vapor. Its height varies depending on the latitude of the place, time of year and day. It is characterized by an increase in temperature with height, an increase in wind speed, and the formation of clouds and precipitation. There are 3 layers in the troposphere:

1. Boundary (friction layer) - from the ground to 1000 - 1500 km. This layer is affected by the thermal and mechanical effects of the earth's surface. The daily cycle of meteorological elements is observed. The lower part of the boundary layer, 600 m thick, is called the “ground layer”. The atmosphere above 1000 - 1500 meters is called the “free atmosphere layer” (without friction).

2. Middle layer is located from the upper boundary of the boundary layer to a height of 6 km. There is almost no influence of the earth's surface here. Weather depend on atmospheric fronts and the vertical balance of air masses.

3. Upper layer lies above 6 km. and extends to the tropopause.

Tropopause – transition layer between the troposphere and stratosphere. The thickness of this layer ranges from several hundred meters to 1 – 2 km, and average temperature from minus 70° - 80° in the tropics.

The temperature in the tropopause layer can remain constant or increase (inversion). In this regard, the tropopause is a powerful delaying layer for vertical air movements. When crossing the tropopause at the flight level, changes in temperature, changes in moisture content and air transparency can be observed. The minimum wind speed is usually located in the tropopause zone or its lower boundary.

Meteorology is a science that studies physical processes and phenomena occurring in the earth’s atmosphere, in their continuous communication and interaction with the underlying surface of the sea and land.

Aviation meteorology is an applied branch of meteorology that studies the influence of meteorological elements and weather phenomena on aviation activities.

Atmosphere. The air envelope of the earth is called the atmosphere.

Based on the nature of the vertical temperature distribution, the atmosphere is usually divided into four main spheres: the troposphere, stratosphere, mesosphere, thermosphere and three transition layers between them: tropopause, stratopause and mesopause (6).

Troposphere - the lower layer of the atmosphere, height 7-10 km at the poles and up to 16-18 km in the equatorial regions. All weather phenomena develop mainly in the troposphere. In the troposphere, clouds form, fogs, thunderstorms, snowstorms occur, aircraft icing and other phenomena occur. The temperature in this layer of the atmosphere drops with altitude by an average of 6.5°C every kilometer (0.65°C per 100%).

Tropopause is a transition layer separating the troposphere from the stratosphere. The thickness of this layer ranges from several hundred meters to several kilometers.

The stratosphere is the layer of the atmosphere lying above the troposphere, up to an altitude of approximately 35 km. The vertical movement of air in the stratosphere (compared to the troposphere) is very weak or almost absent. The stratosphere is characterized by a slight decrease in temperature in the 11-25 km layer and an increase in the 25-35 km layer.

Stratopause is a transition layer between the stratosphere and mesosphere.

The mesosphere is a layer of the atmosphere extending from approximately 35 to 80 km. Characteristic of the mesosphere layer is a sharp increase in temperature from the beginning to a level of 50-55 km and a decrease to a level of 80 km.

Mesopause is a transition layer between the mesosphere and thermosphere.

Thermosphere is a layer of the atmosphere above 80 km. This layer is characterized by a continuous sharp increase in temperature with height. At an altitude of 120 km the temperature reaches +60° C, and at an altitude of 150 km -700° C.

A diagram of the structure of the atmosphere up to an altitude of 100 km is presented.

Standard atmosphere - conditional distribution by height of average values physical parameters atmosphere (pressure, temperature, humidity, etc.). For the international standard atmosphere the following conditions are accepted:

• pressure at sea level equal to 760 mm Hg. Art. (1013.2 MB);
• relative humidity 0%; temperature at sea level is -f 15° C and drops with altitude in the troposphere (up to 11,000 m) by 0.65° C for every 100 m.
• above 11,000 m the temperature is assumed to be constant and equal to -56.5 ° C.

See also:

METEOROLOGICAL ELEMENTS

The state of the atmosphere and the processes occurring in it are characterized by a number of meteorological elements: pressure, temperature, visibility, humidity, clouds, precipitation and wind.

Atmospheric pressure is measured in millimeters mercury or in millibars (1 mm Hg - 1.3332 mb). Atmospheric pressure equal to 760 mm is taken as normal pressure. rt. Art., which corresponds to 1013.25 MB. Normal pressure is close to the average pressure at sea level. Pressure changes continuously both at the surface of the earth and at heights. The change in pressure with altitude can be characterized by the value of the barometric step (the height to which one must rise or fall in order for the pressure to change by 1 mm Hg, or 1 mb).

The value of the barometric stage is determined by the formula

Air temperature characterizes the thermal state of the atmosphere. Temperature is measured in degrees. The temperature change depends on the amount of heat coming from the Sun at a given geographic latitude, the nature of the underlying surface and atmospheric circulation.

In the USSR and most other countries of the world, the centigrade scale is adopted. The main (reference) points in this scale are: 0 ° C - the melting point of ice and 100 ° C - the boiling point of water at normal pressure(760 mmHg). The interval between these points is divided into 100 equal parts. This interval is called “one degree Celsius” - 1° C.

Visibility. The range of horizontal visibility near the ground, determined by meteorologists, is understood as the distance at which an object (landmark) can still be detected by shape, color, and brightness. Visibility range is measured in meters or kilometers.

Air humidity is the content of water vapor in the air, expressed in absolute or relative units.

Absolute humidity is the amount of water vapor in grams per 1 liter3 of air.

Specific humidity is the amount of water vapor in grams per 1 kg of humid air.

Relative humidity is the ratio of the amount of water vapor contained in the air to the amount required to saturate the air at a given temperature, expressed as a percentage. From the relative humidity value you can determine how much this state humidity is close to saturation.

Dew point is the temperature at which the air would reach a state of saturation for a given moisture content and constant pressure.

The difference between air temperature and dew point is called dew point deficit. The dew point is equal to the air temperature if its relative humidity is 100%. Under these conditions, water vapor condenses and clouds and fogs form.

Clouds are a collection of water droplets or ice crystals suspended in the air, resulting from the condensation of water vapor. When observing clouds, note their number, shape and height of the lower boundary.

The amount of clouds is assessed on a 10-point scale: 0 points means no clouds, 3 points - three quarters of the sky is covered with clouds, 5 points - half the sky is covered with clouds, 10 points - the whole sky is covered with clouds (totally cloudy). Cloud heights are measured using radars, searchlights, pilot balloons and airplanes.

All clouds, depending on the location of the height of the lower boundary, are divided into three tiers:

The upper tier is above 6000 m, it includes: cirrus, cirrocumulus, cirrostratus.

The middle tier is from 2000 to 6000 m, it includes: altocumulus, altostratus.

The lower tier is below 2000 m, it includes: stratocumulus, stratus, nimbostratus. The lower tier also includes clouds that extend over a considerable distance vertically, but whose lower boundary lies in lower tier. These clouds include cumulonimbus and cumulonimbus. These clouds stand out in special group clouds vertical development. Cloud cover has greatest influence on aviation activities, since clouds are associated with precipitation, thunderstorms, icing and severe buffeting.

Precipitation is water droplets or ice crystals that fall from clouds to the surface of the earth. According to the nature of precipitation, precipitation is divided into blanket, falling from nimbostratus and altostratus clouds in the form of raindrops average size or in the form of snowflakes; torrential, falling from cumulonimbus clouds in the form of large drops of rain, snow flakes or hail; drizzle, falling from stratus and stratocumulus clouds in the form of very small drops of rain.

Flight in a precipitation zone is difficult due to a sharp deterioration in visibility, a decrease in cloud height, bumpiness, icing in freezing rain and drizzle, and possible damage to the surface of the aircraft (helicopter) due to hail.

Wind is the movement of air relative to the earth's surface. Wind is characterized by two quantities: speed and direction. The unit of measurement for wind speed is meter per second (1 m/sec) or kilometer per hour (1 km/h). 1 m/sec = = 3.6 km/h.

Wind direction is measured in degrees, but it should be taken into account that the countdown is from north pole clockwise: north direction corresponds to 0° (or 360°), east - 90°, south - 180°, west - 270°.

The direction of the meteorological wind (where it blows from) differs from the direction of the aeronautical wind (where it blows) by 180°. In the troposphere, wind speed increases with height and reaches a maximum below the tropopause.

Relatively narrow zones strong winds(at speeds of 100 km/h and above) in the upper troposphere and lower stratosphere at altitudes close to the tropopause are called jet streams. The part of the jet stream where the wind speed reaches its maximum value is called the axis of the jet stream.

In size, jet streams extend thousands of kilometers in length, hundreds of kilometers in width and several kilometers in height.

Very weather dependent: snow, rain, fog, low clouds, strong gusty winds and even complete calm - unfavourable conditions for the jump. Therefore, athletes often have to sit on the ground for hours and weeks, waiting for a “window of good weather.”

Signs of persistent good weather

1. High blood pressure that rises slowly and continuously over several days.
2. Correct daily wind pattern: quiet at night, significant wind strength during the day; on the shores of seas and large lakes, as well as in the mountains, the correct change of winds is:
   • during the day - from water to land and from valleys to peaks,
   • at night - from land to water and from peaks to valleys.
3. in winter clear sky, and only in the evening, when it is calm, thin stratus clouds can float. In summer, on the contrary: cumulus clouds develop and disappear in the evening.
4. Correct daily temperature variation (increase during the day, decrease at night). IN winter time Temperatures are low and high in summer.
5. There is no precipitation; heavy dew or frost at night.
6. Ground fogs that disappear after sunrise.

Signs of persistent bad weather

1. Low pressure, changing little or decreasing even more.
2. Lack of normal diurnal cycle wind; wind speed is significant.
3. The sky is completely covered with nimbostratus or stratus clouds.
4. Prolonged rain or snowfall.
5. Minor temperature changes during the day; relatively warm in winter, cool in summer.

Signs of worsening weather

1. Pressure drop; The faster the pressure drops, the sooner the weather will change.
2. The wind intensifies, its daily fluctuations almost disappear, and the wind direction changes.
3. Cloudiness increases, and the following order of appearance of clouds is often observed: cirrus appears, then cirrostratus (their movement is so fast that it is noticeable to the eye), cirrostratus is replaced by altostratus, and the latter by nimbostratus.
4. Cumulus clouds do not dissipate or disappear in the evening, and their number even increases. If they take the form of towers, then a thunderstorm should be expected.
5. The temperature rises in winter, but in summer there is a noticeable decrease in its diurnal variation.
6. Colored circles and crowns appear around the Moon and Sun.

Signs of improving weather

1. The pressure rises.
2. Cloud cover becomes variable and breaks appear, although at times the entire sky may still be covered with low rain clouds.
3. Rain or snow falls from time to time and is quite heavy, but it does not fall continuously.
4. The temperature drops in winter and rises in summer (after a preliminary decrease).

Aviation meteorology

Aviation meteorology

(from the Greek met(éö)ra - celestial phenomena and logos - word, doctrine) - an applied discipline that studies the meteorological conditions in which aircrafts, and the impact of these conditions on the safety and efficiency of flights, developing methods for collecting and processing meteorological information, preparing forecasts and meteorological support for flights. As aviation develops (the creation of new types of aircraft, the expansion of the range of altitudes and flight speeds, the scale of territories for flight operations, the expansion of the range of tasks solved with the help of aircraft, etc.), aviation is faced with. new tasks are being set. The creation of new airports and the opening of new air routes requires climatic research in the areas of proposed construction and in the free atmosphere along the planned flight routes in order to select optimal solutions to the tasks. Changing conditions around existing airports (as a result economic activity human or under the influence of natural physical processes) requires constant study of the climate of existing airports. Close dependence weather at the earth's surface (the take-off and landing zone of an aircraft) from local conditions requires special research for each airport and the development of methods for forecasting take-off and landing conditions for almost every airport. The main tasks of M. a. as an applied discipline - increasing the level and optimizing flight information support, improving the quality of meteorological services provided (the accuracy of actual data and the accuracy of forecasts), increasing efficiency. The solution to these problems is achieved by improving the material and technical base, technologies and observation methods, in-depth study of the physics of the formation processes of weather phenomena important for aviation and improving methods for forecasting these phenomena.

Aviation: Encyclopedia. - M.: Great Russian Encyclopedia. Chief Editor G.P. Svishchev. 1994 .

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