St. Elmo's fires and mirages, aurora and rainbows, celestial crowns and halos... These and other atmospheric phenomena for many centuries remained a mystery to people, wonderful and frightening, which was often interpreted as a sign.

Currently, all these phenomena have received a scientific explanation. For example, mirages. With an unusual density distribution in lower layers abnormal refraction of light may occur in the air. In this case, in addition to real objects, their imaginary images - mirages - are also visible. Many travelers became their victims. Mirages are different, depending on the direction in which the air density increases or decreases. The desert mirage is the so-called inferior mirage. It occurs when, above a hot surface, as a result of intense upward movements, the air density in the surface layer begins to increase with height. Then the trajectory of the beam turns out to be convex downwards, and the image of a distant object can be seen below its real position, and upside down. In ancient times, travelers, in order to make sure whether they were seeing a mirage or real objects, lit a fire: if there was even a slight movement of air in the desert, then the smoke spreading along the ground quickly dispersed the mirage. There are lateral and superior mirages. Superior mirages often occur in polar regions.

Images of distant objects sometimes seem to fluctuate. It is best seen at night, as the twinkling stars change brightness and sometimes color. This happens because the temperature of the moving air and its density change in the atmosphere, due to which the refractive index of the air changes.

This often occurs as a result of increased wind in the layer below the tropopause, so the twinkling of stars can be a sign of an impending change in weather.

The blue color of the sky is also not accidental. This is the result of the scattering of sunlight on gas molecules, which, due to their size, scatter blue rays better from the entire solar spectrum. The cloudless and clear of impurities the sky, the bluer the color it has, since blue rays, repeatedly scattered by gas molecules, begin to dominate over the rest. On a frosty sunny day, shadows on the snow, illuminated by the diffused light of the sky, appear blue. Against the backdrop of distant black mountains, the sunlit air also seems bluish. With height, the number of scattering particles decreases, the color of the sky becomes darker, gradually turning to deep purple and black.

The disk of the Sun appears yellow to us. This is explained by the fact that the energy of different wavelengths of visible radiation from the Sun decreases unevenly as it passes through. This happens most quickly in the shortest waves - blue and violet. The longer the path of light through the atmosphere, the greater its scattering. Therefore, the lower the Sun is above, the thicker the atmosphere through which the sun’s rays pass, “losing” short waves, the more yellow it appears to us. If there is a lot of dust or droplets and crystals in the air, then the color of the Sun at the horizon may approach red. The colors of dawn are amazing - from golden yellow to purple. Dawn is a set of light phenomena associated with the rising or setting of the Sun. Dawn is a complex combination of processes of scattering, refraction, diffraction of sunlight rays in various. The colors of dawn and their intensity depend on the content of dust particles in the atmosphere. During strong volcanic eruptions, great amount dust and ash. Such particles enhance the scattering of sunlight and cause unusually bright dawns. An example is Krakatoa () in 1883, when huge masses of volcanic ash were raised to a height of over 50 km. Air currents carried them all over to the globe And more than a year caused abnormally bright and prolonged dawns. In the part of the sky opposite the sunset, anti-dawn is observed. There is also a change in color tones from purple to violet. With the onset of twilight, a gray-blue shadow of the Earth appears in this part of the sky. In a dark sky, after the end or before the beginning of astronomical twilight, the phenomenon of zodiacal light can be observed. This is a gentle glow above the invisible Sun in the shape of an inclined cone directed along the ecliptic. It is believed that the zodiacal light is the result of the scattering of sunlight by cosmic (meteor) dust.

The "green ray" phenomenon explained by refraction - the refraction of light. Seeing a “green ray” is considered a good omen. “Green beam” - a short flash of green color on upper limit solar disk. This phenomenon is observed at sunrise or sunset and is explained by atmospheric refraction, which seems to lift the star above the horizon. As the wavelength decreases, the influence of refraction increases, so it turns out that the “green” Sun sets a little later than the “red” one and we see a “green ray”. A rainbow is an arc of color centered at a point opposite the Sun. A rainbow appears against the background of rain or a rain cloud. There can be several rainbows. The outer part of the main rainbow (42° radius) is red, followed by orange, yellow, green, cyan, indigo, and violet. Above the main rainbow there is also a second one, with the reverse arrangement of colors. The phenomenon of a rainbow is explained by the refraction of light in relatively large drops of water.

Halo- light, predominantly colored circles or arcs, light pillars or spots near the Sun or Moon. A halo occurs when light is refracted not in drops, but in ice crystals, such as those found in cirrostratus clouds. Most often, a halo with an angular radius of 22° is observed - a bright circle around the disk of the Sun or Moon. WITH inside the halo has the brightest color and can acquire a reddish tint, turning towards the outer edge into yellow and bluish, and then into whitish, merging with the color of the sky. Less commonly seen is a larger circle with an angular radius of 46°. Sometimes a white horizontal circle also appears, often covering the entire sky. At its intersection with the vertical small circle, false suns and moons may appear.

Crowns(also called a halo) can be observed around the Sun or Moon in translucent clouds (altocumulus or altostratus). These light circles, in which red and green colors are most clearly distinguishable, are adjacent close to the disk of the luminary. The crowns can be arranged in the form of several rings nested inside each other. This optical phenomenon is caused by diffraction (from the Latin diffractus - broken) of light on the smallest droplets of water in clouds or fogs. This phenomenon can also be observed with artificial light sources.

A crown of color may form around the shadow cast by an airplane on the clouds below, or the shadow of a person in a dewy meadow. This type of crown is called gloria. The “Brocken ghost” (named after the Brocken mountain in Saxony) was nicknamed a gloria that appeared around the shadow of the observer’s head on the close surface of a cloud ridge or on a wall (this most often happens in the mountains). Distorting the distance to the shadow gives the effect of a giant ghostly figure, around whose head colored rings may appear.

Polar Lights- a spectacular glow of the sky with flashes. It is often observed in the high latitudes of the Northern and Southern hemispheres. The aurora occurs due to the luminescence (glow) of rarefied air at altitudes from several tens to hundreds of kilometers. During the period of disturbances magnetic field The Earth's charged particles (electrons and protons), moving along magnetic lines of force, invade the atmosphere, falling to altitudes of 100 - 150 km. There they begin to collide with atoms and molecules of atmospheric gas, which, when excited, in turn emit light. The aurora is observed simultaneously in both hemispheres at all longitudes in a strip about 100 km wide or less. The most frequent recurrence of this phenomenon is recorded in the band 20 - 25° from the poles. This is where the magnetic power lines enter the atmosphere. There are exceptions. So, in 1872, residents of the city of Pereslavl observed an unusual blazing sky.

Rapid changes in color, intensity and position of the aurora create uniquely beautiful pictures running across the sky. The forms of the aurora are varied - arcs, rays, ribbons, coronas and general glow. Most often, the aurora is colored in bluish-white or yellow-green tones, less often in red and violet. Its duration can range from tens of minutes to several days.

St. Elmo's Fire- another phenomenon associated with the electrical properties of the atmosphere. It has always frightened superstitious sailors, and these are just discharges in the form of luminous beams that appear at the sharp ends of tall objects (masts, towers, etc.) with a very high electric field intensity in the atmosphere (during dust storms). This “strange” phenomenon was periodically observed in stormy weather in the form of a glow above the medieval towers of St. Elmo’s Church, hence the name “St. Elmo’s Lights.” In ancient times, the glow in the form of beams that appeared around towers and ship masts was often mistaken for an unkind sign of fate.

Ball lightning- This is a luminous ball with a diameter of tens of centimeters. It moves with air movement and can explode upon contact with ground objects. According to some assumptions, the source of ball lightning is the hot channel of ordinary lightning, and its composition is unstable compounds of nitrogen and oxygen, the formation of which requires large amounts of energy. When cooled to a certain critical temperature, the substance of ball lightning instantly disintegrates into nitrogen and oxygen with the release of absorbed energy, resulting in an explosion.

V.V.Brovkin

Atmospheric phenomena are an important element of weather: whether it is raining or snowing, whether there is fog or a dust storm, whether a blizzard or thunderstorm is raging, greatly influences how we perceive current state atmosphere by living beings (humans, animals, plants), and the impact of weather on open-air machines and mechanisms, buildings, roads, etc. Therefore, observations ofATMOSPHERIC PHENOMENA (their correct determination, recording of start and stop times, intensity fluctuations) on the network of weather stations have great importance. However, such observations are available not only to professionals, but also to a wide range of nature lovers; To do this, you need to study the descriptions of the phenomena and understand what (CLOUDY conditions, WIND, TEMPERATURE range, etc.) this or that is associated withWEATHER PHENOMENON .

Note: descriptions of the phenomena are given mainly as they are used when encoding weather reports (code forms METAR, SYNOP and others) transmitted via communication channels (including those published on the Internet in general and on our website in particular). For a number of phenomena, there are differences in their names and designations when recording observation results in documentation (books and observation logs) kept at weather stations.

In such cases, an additional explanation is added at the end of the description of the phenomenon, marked JOURNAL. For those phenomena that are recorded only in station documentation and are not transmitted in reports, the description begins directly with the word JOURNAL.

Precipitation falling on the earth's surface Cover precipitation

They are characterized by monotony of loss without significant fluctuations in intensity. They start and stop gradually. The duration of continuous loss is usually several hours (and sometimes 1-2 days), but in in some cases light precipitation can last half an hour to an hour. Usually fall from nimbostratus or altostratus clouds; Moreover, in most cases the cloudiness is continuous (10 points) and only occasionally significant (7-9 points, usually at the beginning or end of the precipitation period). Sometimes weak short-term (half an hour to an hour) precipitation is observed from stratus, stratocumulus, altocumulus clouds, with the number of clouds being 7-10 points. IN frosty weather(air temperature below -10...-15°) light snow may fall from a partly cloudy sky.

Rain

Liquid precipitation in the form of droplets with a diameter of 0.5 to 5 mm. Individual raindrops leave a mark on the surface of water in the form of a diverging circle, and on the surface of dry objects - in the form of a wet spot.

Freezing rain

Liquid precipitation in the form of droplets with a diameter of 0.5 to 5 mm, falling at negative air temperatures (most often 0...-10°, sometimes up to -15°) - falling on objects, the drops freeze and form ice.

MAGAZINE: noted rain.

freezing rain

Solid precipitation that falls at negative air temperatures (most often 0...-10°, sometimes up to -15°) in the form of solid transparent ice balls with a diameter of 1-3 mm. Inside the balls there is unfrozen water - when falling on objects, the balls break into shells, water flows out and forms ice.

Snow

Solid precipitation that falls (most often at negative air temperatures) in the form of snow crystals (snowflakes) or flakes. With light snow, horizontal visibility (if there are no other phenomena - haze, fog, etc.) is 4-10 km, with moderate snow 1-3 km, with heavy snow - less than 1000 m (in this case, snowfall increases gradually, so Visibility values ​​of 1-2 km or less are observed no earlier than an hour after the start of snowfall). In frosty weather (air temperature below -10...-15°), light snow may fall from a partly cloudy sky.

MAGAZINE: the phenomenon is noted separately wet snow- mixed precipitation that falls at positive air temperatures in the form of melting snow flakes.

Rain with snow

Mixed precipitation that falls (most often at positive air temperatures) in the form of a mixture of drops and snowflakes. If rain and snow fall at sub-zero air temperatures, precipitation particles freeze onto objects and form ice.

MAGAZINE: two phenomena are observed simultaneously - rain And snow.

Basic meteorological quantities. Atmospheric phenomena.

TO meteorological quantities include temperature, pressure, air humidity, wind speed and direction, cloudiness, precipitation, meteorological visibility range.

Atmospheric phenomena- This physical processes, which are accompanied by a sharp qualitative change in the state of the atmosphere (rain, snow, frost, rainbow, thunderstorm, aurora, mirage, etc.)

Weather is a set of meteorological quantities and atmospheric phenomena in this moment or a period of time in a given place.

Climate is the long-term weather pattern in a given geographic area.

Meteorological quantities:

Temperature (air, soil, water) is a characteristic of the thermal state of the body, a measure of the body’s heating.

Air, like any body, always has a temperature different from absolute zero. The air temperature at every point in the atmosphere changes continuously; in different places on the Earth at the same time it is also different. U earth's surface air temperature varies over a fairly wide range: its extreme values ​​observed so far are slightly below +60 °C (at tropical deserts) and about -90 °C (on the mainland of Antarctica).

With altitude, air temperature changes in different layers and in different cases in different ways. On average, it first drops to a height of 10-15 km, then increases to 50-60 km, then falls again, etc.

The temperature of air, as well as soil and water in the SI system is expressed in degrees international temperature scale, or the Celsius scale (°C), generally accepted in physical measurements. The zero of this scale corresponds to the temperature at which ice melts, and 100 ° C corresponds to the boiling point of water (both at a pressure of 1013 hPa).

Along with the Celsius scale, the absolute temperature scale (Kelvin scale) is widely used (especially in theory). The zero of this scale corresponds to the complete cessation of molecular movement, i.e. lowest temperature. On the Celsius scale it would be -273.1°C. The absolute scale unit, called Kelvin, is equal to the Celsius scale unit: 1K = 1°C. On an absolute scale, temperature can only be positive, i.e. above absolute zero. In formulas, temperature on an absolute scale is denoted by T, and temperature in Celsius – through t.

To change from Celsius temperature to Kelvin temperature, use the formula:

ТК = t°С+273.1

Another one temperature scale, which is used, in particular, in the USA, proposed by G. Fahrenheit in 1724, is the Fahrenheit scale, 1 degree of which (1 °F) is equal to 1/180 of the difference between the boiling temperatures of water and the melting of ice, and the melting point of ice has a temperature of +32 ° F. Temperature on the Fahrenheit scale is related to temperature on the Celsius scale (t °C) by the relation

t °C = 5 / 9 (t °F-32),

Thus, a degree of Fahrenheit is almost half the size of a degree on a centigrade scale, and the zeros of these scales do not coincide.

Zero on the Fahrenheit scale corresponds to a temperature of -17.8° on the centigrade scale

Pressure – force of hydrostatic air pressure. per unit area.

Atmospheric pressure is measured by the weight of the above-lying column of air per unit of horizontal surface. The total mass of the atmosphere with which it presses on the Earth’s surface is 5.15 * 1015 tons.

Since the time of Toricelli (XU11), air pressure has been measured by height mercury in millimeters or inches, when various calculation methods for analyzing and forecasting the state of the atmosphere began to be introduced into practice, it turned out that the linear measure was millimeters. not related to physical essence pressure as force is extremely inconvenient. Therefore, in the 20s. Norwegian meteorologist V. Bjerkens proposed a new unit for measuring atmospheric pressure - millibar (mbar).

A millibar is a unit of atmospheric pressure equal to 1000 dynes per 1 cm2 (1 dyne is the force that imparts an acceleration of 1 cm/s2 to a mass of 1 g).

In millibars normal pressure(average pressure at sea level at a latitude of 45° at an air temperature of 0°C) is 1013.25 mbar or 760 mmHg, and the standard pressure is taken to be 1000 mbar or 750 mmHg.

Currently, in the SI system of units, pressure is measured in Pascals (Pa). Pascal is the pressure caused by a force of 1 N, uniformly distributed over an area of ​​1 m2, 100 Pa = 1 hPa. One hectopascal is numerically equal to one millibar.

Pressure units: hPa, mb, mmHg.

[P] = = [Pa],

1hPa = 100Pa = 1mb

1mmHg = 4/3 =1.333 hPa

1hPa = ¾ = 0.75mmHg

Air humidity

One of the components of atmospheric air is steam. Its greater or lesser amount in the air determines the humidity or dryness of the climate, human living conditions and plant growth.

Absorbing most the earth's own radiation and transferring part of the received heat to the underlying surface, forming counter radiation, water vapor reduces the cooling intensity of the underlying surface when there is no incoming solar radiation. Consequently, the more water vapor there is in the atmosphere, the slower the temperature of the underlying surface, and hence the surrounding air, decreases after sunset. And since increased air humidity is usually observed when approaching warm front or a cyclone, then an increase in air temperature in the evening is one of the signs of worsening weather.

Condensation of water vapor on ground objects leads to the formation of dew and frost. frost, etc. Condensation of water vapor in the surface layer of the atmosphere leads to the formation of fogs, which significantly impair visibility. Condensation of water vapor in a free atmosphere leads to the formation various forms clouds and precipitation. Condensation and evaporation are accompanied by the release and absorption of a large amount of heat, and this further increases the role of steam in the energy and thermodynamics of the atmosphere.

Atmospheric air, especially in the lower layers, always contains some amount of water vapor. At a certain temperature, which depends on the amount of water vapor, the water vapor in the air can reach saturation. In this case, the air is called saturated.

To characterize air humidity, several values ​​are used that reflect:

1. absolute content of water vapor in the air (elasticity, absolute, specific humidity),

2. the degree of proximity of water vapor to the saturation state (relative humidity, humidity deficit, dew point).

1. Water vapor, like any gas, has elasticity (pressure). Vapor pressure(e) , Pa is less than the saturation elasticity (E).

The greater the difference E - e, the drier the air and the more intense the evaporation.

Absolute humidity (a)- weight water vapor contained in a unit volume of air, kg/m3.

The relationship between absolute humidity and water vapor pressure is as follows:

a =2.17*10 -3 e/T,

where a - absolute humidity, kg/m 3 ; e - water vapor pressure, Pa;

T - air temperature, K

Specific humidity (q)- mass of water vapor contained in a unit mass of moist air, g/kg:

q=622e/P,

where P is air pressure, Pa; e - water vapor pressure, Pa.

2. The feeling of dryness or dampness of air is not related to absolute moisture content (elasticity, absolute or specific humidity), but to how close water vapor is to saturation, and is characterized by moisture deficiency and relative humidity.

Humidity deficit(d), hPa is the difference between the saturation elasticity (E) at a given temperature and the elasticity of water vapor (e) contained in the air;

d = E – e

Relative humidity (r), % - the ratio of the mass of water vapor contained in the air to the mass of water vapor necessary to saturate the air at a given temperature

r=e/E*100

If the amount of water vapor remains the same and the air temperature increases, the relative humidity decreases. When the air temperature decreases, while the amount of water vapor in the air remains constant, the relative humidity increases.

Each air temperature value corresponds to a very specific amount of water vapor that will saturate the air, and the lower the temperature, the less water vapor is required to saturate it.

The temperature to which the air needs to be cooled constant pressure so that the water vapor contained in it reaches saturation states is called dew point and is designated Greek letterτ. Dew point is an important and convenient characteristic of air moisture content. In particular, it is easy to judge the probability of fog formation. In saturated air it coincides with the air temperature, in all other cases it is lower.

Wind

Depending on the distribution of atmospheric pressure, the air constantly moves in a horizontal direction. This horizontal movement is called by the wind. The speed and direction of the wind changes all the time. Average wind speeds at the earth's surface are close to 5-10 m/s. But sometimes, in strong atmospheric vortices, wind speeds at the earth's surface can reach or exceed 50 m/s. In high layers of the atmosphere, in the so-called jet streams, wind speeds of up to 100 m/s or more are regularly observed.

Vertical components are also added to the horizontal air transfer. They are usually small compared to horizontal transfer, on the order of centimeters or tenths of a centimeter per second. Only under special conditions, with so-called convection, in small areas of the atmosphere, the vertical components of air velocity can reach several meters per second.

The wind always has turbulence. This means that individual amounts of air in a wind flow do not move along parallel paths. Numerous randomly moving vortices and jets of different sizes appear in the air. Individual amounts of air carried away by these vortices and jets, the so-called elements of turbulence, moving in all directions, including perpendicular to the general or average direction of the wind and even against it. These elements of turbulence are not molecules, but large volumes of air, the linear dimensions of which are measured in centimeters, meters, tens of meters. Thus, the general transport of air in a certain direction and at a certain speed is superimposed on a system of chaotic, disorderly movements of individual elements of turbulence along complex intertwining trajectories.

The turbulent nature of air movement can be clearly seen by watching snowflakes falling in the wind. Snowflakes do not fall vertically downward and do not fall at the same angle to the vertical. They dance randomly in the air, flying up and down, describing complex loops. This is explained precisely by the fact that snowflakes participate in the movement of turbulence elements, thereby making this movement visible. The turbulent nature of the wind is also revealed when observing the spread of smoke in the atmosphere.

Characteristics of wind - speed and direction.

Wind speed. Measured in m/s and km/h, knots and Beaufort scale points..

1m/s = 3.6 km/h

1 knot = 1 nautical mile/hour = 0.51 m/s

Beaufort scale:

Direction of the wind- direction, where The wind's blowing. Expressed in horizon points or angular degrees.

Cloudiness In the atmosphere, as a result of condensation of water vapor, accumulations of condensation products - droplets and crystals - are formed. They are called clouds. Cloud elements—droplets and crystals—are so small that they are balanced by friction. The steady-state speed of falling drops in still air is equal to several fractions of a centimeter per second, and the falling of crystals is even less. In the presence of turbulent movement, small drops and crystals remain in a suspended state for a long time - they move slightly down and up.

Clouds are carried by air currents. If the relative humidity of the air decreases, the clouds evaporate. Under certain conditions, some cloud elements become so large that they fall out of the cloud in the form of precipitation. In this way, water returns from the atmosphere to the earth's surface.

When condensation occurs directly near the earth's surface, the resulting accumulations of condensation products are called fogs. There is no fundamental difference in the structure of clouds and fogs. In the mountains, cases are possible when a cloud appears on the mountain slope itself. For an observer looking from below, from the valley, the phenomenon will appear as a cloud; for an observer on the very foggy slope. Clouds exist sometimes a short time. For example, the lifetime of an individual cumulus cloud can be 10-15 minutes. But even when a cloud exists for a long time, this does not mean that it is in an unchanged state. In reality, cloud elements are constantly evaporating and re-emerging. There is a certain process of cloud formation for a long time; the cloud is only the currently visible part of the total mass of water involved in this process. This is especially noticeable when clouds form over the mountains. When air continuously flows over a mountain, it cools adiabatically as it rises, so much so that clouds form at a certain altitude. These clouds seem immovably tied to the crest of the ridge. But in reality they move with the air and evaporate all the time in the front part, where the flowing air begins to fall, and are re-formed in the rear part from water vapor coming with the rising air.

The weightiness of clouds is also deceptive. If a cloud does not change its height, this does not mean that its constituent elements do not fall out. Drops in a cloud can descend, but when they reach the bottom of the cloud, they move into unsaturated air and evaporate. As a result, the cloud will appear to be at the same level for a long time.

Meteorological visibility range

Distant objects are seen worse than close ones, not only because their apparent size decreases. Even very large objects at a certain distance from the observer become poorly visible due to the turbidity of the atmosphere through which they are visible. This haze is caused by light scattering in the atmosphere. It is clear that it increases with increasing aerosol impurities in the air.

Meteorological visibility range is one of the characteristics of atmospheric transparency, and it should be distinguished from the real visibility range of various objects, which depends not only on the transparency of the atmosphere, but also on the color of the objects, their size, distance from the observation point, illumination and background.

Meteorological visibility range is the greatest distance from which, during daylight hours, an absolutely clear body of sufficiently large angular dimensions (more than 15 arc minutes) can be detected against the background of the sky near the horizon (or against the background of air haze).

The visibility range is most often determined by eye using certain, pre-selected objects (dark against the sky), the distance to which is known. But there are also a number of photometric instruments for determining visibility.

In very clean air, for example of arctic origin, the visibility range can reach hundreds of kilometers. Scattering of light in such air is produced mainly by molecules atmospheric gases. In air containing a lot of dust or condensation products, the visibility range can be reduced to several kilometers or even meters. So, in light fog, the visibility range is 500-1000 m, and in heavy fog or a strong sandstorm can drop to tens or even several meters.

Atmospheric phenomena

As already mentioned, atmospheric phenomena are precipitation (rain, snow, drizzle, hail), dew, frost, ice, fog, haze, haze, dust storm, thunderstorm, tornado, etc.

Precipitation falling from clouds

Rain is precipitation that falls in the form of drops. Individual drops of rain, falling into the water, always leave a trail in the form of a diverging circle, and on a dry deck - a trail in the form of a wet spot.

Cover rain - precipitation falling from nimbostratus clouds. It is characterized by a gradual beginning and end, precipitation is continuous or with short breaks, but without sharp fluctuations in intensity, and in most cases the clouds cover the entire sky with a continuous, homogeneous cover. Sometimes weak and short continuous rain can also fall from altostratus, stratocumulus and other clouds.

Rain shower - rain, characterized by the suddenness of the beginning and end of the fall, a sharp change in intensity. The name "heavy rain" refers to the nature of the rainfall, and not the amount of precipitation that falls, which may be insignificant. View of the sky during heavy rain; The clouds are predominantly cumulonimbus, sometimes blue-lead in color, with temporary clearings occurring. Rain showers are often accompanied by thunderstorms.

Drizzle - precipitation that falls in the form of very small droplets. The droplets are so small that their fall is almost invisible to the eye; they are suspended in the air and participate even in its weak movement. Drizzle should not be mixed with light rain, the drops of which, although very small, can be observed falling: drops of drizzle settle slowly and their fall is imperceptible. When it drizzles, there are no circles on the water. Drizzle usually falls from stratus clouds or fog.

Snow - precipitation in the form of individual snow crystals or flakes, sometimes reaching large sizes

Cover snow- precipitation falling from nimbostratus clouds continuously or with short breaks. In most cases, clouds cover the entire sky solid uniform cover. Cover snow can also fall from altostratus, stratocumulus, stratus, etc.

Shower snow- snow, characterized by the suddenness of the beginning and end of the fall, sharp fluctuations in intensity and the short duration of its strongest fall. The appearance of the sky during heavy snow: gray or dark gray cumulonimbus clouds alternating with short-term clearings.

IN polar seas Frequent, very short, but heavy snowfalls are often observed, which are called snow charges.

Wet snow - precipitation that falls in the form of melting snow or sleet.

Snow pellets - precipitation that falls in the form of opaque snow grains of white or matte white color, spherical in shape, with a diameter of 2 to 5 mm. The grains sometimes have the shape of a cone with a segment-shaped base. They are small, fragile and easily crushed by fingers. Snow pellets fall mainly at temperatures around 0°C, often before or simultaneously with snow. In spring and autumn, snow pellets often fall from cumulonimbus clouds in short showers during squalls in cold air masses.

Snow grains - sediments in the form of sticks or grains, similar to snow pellets, but much smaller, matte white in color. The diameter of the grains does not exceed 1 mm. Snow grains usually fall in small quantities and mostly from stratus clouds.

Ice grains - precipitation that falls in the form of small transparent ice grains, in the center of which there is a small white opaque core. The diameter of the grains does not exceed 3mm . The grains are hard and require little force to crush. When the air temperature is above 0° C, their surface is wet. Ice pellets usually fall from cumulonimbus clouds, often along with rain, and are observed mainly in spring and autumn.

hail- precipitation that falls in the form of pieces of ice of various shapes. Hailstone cores are usually opaque, sometimes surrounded by a transparent layer or several transparent and opaque layers. The diameter of hailstones is about 5 mm, in in rare cases reaches several centimeters. Large hailstones reach a weight of several grams, and in exceptional cases - several tens of grams. Hail falls mainly in the warm season from cumulonimbus clouds and is usually accompanied by heavy rain. Severe large hail is almost always associated with thunderstorms and strong winds.

freezing rain - precipitation, which is small, hard, completely transparent ice balls with a diameter of 1 to 3 mm, formed from raindrops when they freeze in the lower layers of the atmosphere. They differ from ice pellets by the absence of an opaque white core.

Optical phenomena in nature

Phenomena associated with the refraction of light.

Mirages.

In an inhomogeneous medium, light travels non-linearly. If we imagine a medium in which the refractive index changes from bottom to top, and mentally divide it into thin horizontal layers, then, considering the conditions for the refraction of light when moving from layer to layer, we note that in such a medium the light ray should gradually change its direction.

The light beam undergoes such bending in the atmosphere, in which for one reason or another, mainly due to its uneven heating, the refractive index of the air changes with altitude.

The air is usually heated by the soil, which absorbs energy from the sun's rays. Therefore, the air temperature decreases with height. It is also known that air density decreases with height. It has been established that with increasing altitude, the refractive index decreases, so rays passing through the atmosphere are bent, bending towards the Earth. This phenomenon is called normal atmospheric refraction. Due to refraction, the celestial bodies appear to us somewhat “raised” (above their true height) above the horizon.


Mirages are divided into three classes.
The first class includes the most common and simple in origin, the so-called lake (or lower) mirages, which cause so much hope and disappointment among desert travelers.

The explanation for this phenomenon is simple. The lower layers of air, heated from the soil, have not yet had time to rise upward; their refractive index of light is less than the upper ones. Therefore, rays of light emanating from objects, bending in the air, enter the eye from below.

To see a mirage, there is no need to go to Africa. It can be observed on a hot, quiet summer day and above the heated surface of an asphalt highway.

Mirages of the second class are called superior or distant vision mirages.

They appear if the upper layers of the atmosphere turn out to be especially rarefied for some reason, for example, when heated air gets there. Then the rays emanating from earthly objects are bent more strongly and reach the earth's surface, going at a large angle to the horizon. The observer's eye projects them in the direction in which they enter it.

Apparently, the Sahara Desert is to blame for the fact that a large number of distant vision mirages are observed on the Mediterranean coast. Hot air masses rise above it, then are carried north and create favorable conditions for the occurrence of mirages.

Superior mirages are also observed in northern countries when the wind blows warm southerly winds. The upper layers of the atmosphere are heated, and the lower layers are cooled due to the presence of large masses of melting ice and snow.

Mirages of the third class - ultra-long-range vision - are difficult to explain. However, assumptions have been made about the formation of giant air lenses in the atmosphere, about the creation of a secondary mirage, that is, a mirage from a mirage. It is possible that the ionosphere plays a role here, reflecting not only radio waves, but also light waves.

Phenomena related to light dispersion

Rainbow is a beautiful celestial phenomenon that has always attracted human attention. In earlier times, when people still knew very little about the world around them, the rainbow was considered a “heavenly sign.” So, the ancient Greeks thought that a hundred rainbows were the smile of the goddess Iris. A rainbow is observed in the direction opposite to the Sun, against the background of rain clouds or rain. A multi-colored arc is usually located at a distance of 1-2 km from the observer Ra, sometimes it can be observed at a distance of 2-3 m against the background of water drops formed by fountains or water sprays

The rainbow has seven primary colors, smoothly transitioning from one to another.

The type of arc, the brightness of the colors, and the width of the stripes depend on the size of the water droplets and their number. Large drops create a narrower rainbow, with sharply prominent colors, while small drops create a blurry, faded and even white arc. That is why a bright narrow rainbow is visible in the summer after a thunderstorm, during which large drops fall.

The theory of the rainbow was first given in 1637 by R. Descartes. He explained rainbows as a phenomenon related to the reflection and refraction of light in raindrops.

The formation of colors and their sequence were explained later, after unraveling the complex nature of white light and its dispersion in the medium. The diffraction theory of rainbows was developed by Ehry and Pertner.

Phenomena associated with the interference of light

White circles of light around the Sun or Moon that result from the refraction or reflection of light by ice or snow crystals in the atmosphere are called halos. There are small water crystals in the atmosphere, and when their faces form a right angle with the plane passing through the Sun, the one observing the effect and the crystals will see a characteristic white halo surrounding the Sun in the sky. So the faces reflect light rays with a deviation of 22°, forming a halo. During the cold season, halos formed by ice and snow crystals on the surface of the earth reflect sunlight and scatter it into different directions, creating an effect called "diamond dust".

Most famous example The large halo is the famous, often repeated "Broken Vision". For example, a person standing on a hill or mountain with the sun rising or setting behind him discovers that his shadow falling on the clouds becomes incredibly huge. This happens because tiny drops of fog refract and reflect sunlight in a special way. The phenomenon got its name from the Brocken peak in Germany, where, due to frequent fogs, this effect can be regularly observed.

Parhelia.

"Parhelium" translated from Greek means "false sun." This is one of the forms of a halo (see point 6): one or more additional images of the Sun are observed in the sky, located at the same height above the horizon as the real Sun. Millions of ice crystals with a vertical surface, reflecting the Sun, form this beautiful phenomenon.

Parhelia can be observed in calm weather when the Sun is low, when significant amount The prisms are positioned in the air so that their main axes are vertical, and the prisms slowly descend like small parachutes. In this case, the brightest refracted light enters the eye at an angle of 220 from the faces located vertically, and creates vertical pillars on both sides of the Sun along the horizon. These pillars can be particularly bright in some places, giving the impression of a false Sun.

Polar lights.

One of the most beautiful optical phenomena of nature is the aurora. It is impossible to convey in words the beauty of the auroras, iridescent, flickering, flaming against the background of the dark night sky in the polar latitudes.

In most cases, auroras have a green or blue-green hue with occasional spots or a border of pink or red.

Auroras are observed in two main forms - in the form of ribbons and in the form of cloud-like spots. When the radiance is intense, it takes the form of ribbons. Losing intensity, it turns into spots. However, many tapes disappear before they have time to break into spots. The ribbons seem to hang in the dark space of the sky, resembling a giant curtain or drapery, usually stretching from east to west for thousands of kilometers. The height of the curtain is several hundred kilometers, the thickness does not exceed several hundred meters, and it is so delicate and transparent that the stars are visible through it. The lower edge of the curtain is quite clearly and sharply outlined and is often tinted in a red or pinkish color, reminiscent of a curtain border; the upper edge gradually disappears in height and this creates a particularly impressive impression of the depth of space.

There are four types of auroras:

1. Homogeneous arc - the luminous strip has the simplest, calmest shape. It is brighter from below and gradually disappears upward against the background of the sky glow;

2. Radiant arc - the tape becomes somewhat more active and mobile, it forms small folds and streams;

3. Radiant stripe - with increasing activity, larger folds overlap small ones;

4.As activity increases, folds or loops expand to huge size(up to hundreds of kilometers), the lower edge of the tape shines with pink light. When activity subsides, the folds disappear and the tape returns to a uniform shape. This suggests that a homogeneous structure is the main form of the aurora, and folds are associated with increasing activity.

Radiances of a different type often appear. They cover the entire polar region and are very intense. They occur during an increase in solar activity. These auroras appear as a whitish-green glow throughout the polar cap. Such auroras are called squalls.

Conclusion

Once upon a time, the mirages “The Flying Dutchman” and “Fata Morgana” terrified sailors. On the night of March 27, 1898, among Pacific Ocean The crew of the Matador were frightened by a vision when, in the calm of midnight, they saw a ship 2 miles (3.2 km) away that was struggling with strong storm. All these events actually took place at a distance of 1700 km.

Today, everyone who knows the laws of physics, or rather its branch of optics, can explain all these mysterious phenomena.

In my work I did not describe all optical phenomena of nature. There are a lot of them. We admire blue sky, ruddy dawn, blazing sunset - these phenomena are explained by the absorption and scattering of sunlight. Working with additional literature, I became convinced that the questions that arise when observing the world around us can always be answered. True, you need to know the basics of natural sciences.

CONCLUSION: Optical phenomena in nature are explained by the refraction or reflection of light, or the wave properties of light - dispersion, interference, diffraction, polarization, or the quantum properties of light. The world is mysterious, but we know it.

World atmospheric phenomena very rich. It can be both beautiful and terrible. Therefore, to know their nature, the very essence of the phenomenon that we observe, to be able to foresee possible Negative consequences- this is an important body of knowledge that will help you better understand what is happening around you. Of course, the entire range of unusual natural phenomena in the Earth’s atmosphere cannot be described in one article, but we will try to talk about the strangest, unusual and frightening ones.

As we approach atmospheric front or with vigorous transfer of air from remote areas, on the leeward side of mountain ranges, behind the ridges and individual peaks at an altitude of two to fifteen kilometers, you can sometimes see rare a natural phenomenon- lenticular or lenticular clouds. Given their characteristic shape and the fact that they do not move, no matter how strong the wind, people often associate their appearance with evidence of the presence of aliens on our planet. Indeed, they are very reminiscent of shots from the movie “Independence Day,” aren’t they?

In fact, strong horizontal air currents encounter mountain obstacles and form air waves over the mountain tops. As a result, water vapor condenses in the air when it reaches the dew point height and evaporation occurs when the air moves downward. Therefore, the clouds do not change their position in space, but stand rooted to the spot in the sky.

When you see such a luminous ring in the sky around the sun or moon, you involuntarily become a little scary. This sight really looks ominous. The effect is rare; out of habit, you can fall into religion. It is not for nothing that in the old days this phenomenon was considered a bad omen. Especially if the halo took the shape of a cross or twins of the luminary appeared. A halo forms only during severe frosts and high air humidity. Under these conditions, small ice crystals form in the air, which act like many lenses, reflecting or refracting the light source. There are many types of halos, and their appearance depends on the shape and arrangement of the ice crystals, as well as the light source.

For example, sometimes you can see several Suns in the sky. The reason for this is the same ice crystals hanging in the atmosphere and creating the effect of millions of lenses. Water freezes in the upper atmosphere into small, flat, hexagonal ice crystals. The planes of these crystals, spinning, gradually descend to the ground, oriented parallel to the surface of the earth. At sunrise or sunset, the observer's line of sight can pass through this very plane, and each crystal behaves like a miniature lens, refracting or reflecting sunlight.
The effect of light refraction from millions of ice particles leads to the phenomenon of a false sun. In real life it looks creepy. Believe me, the impression of what you saw will not fade over the years.

If you light a fire in the mountains at night, choosing weather with low clouds and standing with your back to the fire, a colored halo will appear around your head, and your shadow will appear on the clouds. There will be a bluish ring inside, a reddish one outside, then the rings can be repeated with less intensity. This phenomenon is called gloria. Essentially, it is an optical phenomenon observed on clouds that are located below the observer or directly in front of him at a point directly opposite to the source of illumination. In the East, gloria was called the “light of Buddha.” The colored halo that appears in this way was interpreted as the degree of enlightenment or closeness to the deities of the subject, in particular the Buddha.

In fact, gloria is explained by the diffraction of light, and this ghostly halo is nothing more than their own shadow, greatly exaggerated and cast by the rays of the sun onto nearby clouds or fog. The degree of magnification will be greater the further away the wall of fog or cloud is. The unexpected appearance of a bright giant gloria makes a strong impression. A man does something, for example, raises his hand with an ice ax, and his shadow in the center of the gloria repeats all his movements. This phenomenon was first described from observations on the Brocken mountain in the Harz mountain range in Central Germany and therefore also received the name of the Brocken ghost.

Rolling cloud "Morning Glory".

Can you imagine a powerful wave that has a single crest and moves without changing speed or shape? No? Then look - this is exactly what Morning Glory looks like, the only clouds that have given name. The Morning Glory rolling cloud is a cloud up to 1500 km long, 1-2 km high and moving at speeds of up to 40 km/h. These clouds appear mainly off the coast of Australia, in places with high humidity and increased atmospheric pressure. The physics here is this: the sun heats the front of the cloud and an upward movement of air occurs in it, which spins the cloud.

A fire tornado is an extraordinary phenomenon that occurs at the site of fires. Also known as fire devil or fire whirlwind. This is a rare phenomenon in which the fire, under certain conditions, depending on temperature and air flows, acquires vertical vorticity. Vertically rotating pillars can reach from 10 to 65 meters in height, but only in the last few minutes of their existence. And in certain winds they can be even higher.

A firestorm is formed when scattered fires unite into one huge fire. The air above it heats up, its density decreases and it rises. From below, cold air masses from the periphery enter in its place. The arriving air also heats up. And it turns out something like a blacksmith’s bellows pumping oxygen. Stable centripetal directional flows are formed, screwing counterclockwise from the ground to a height of up to five kilometers. There is an effect chimney. The temperature rises to 600˚C. The whirlwind of flame burns until everything that can burn is burned.

Mother-of-pearl and noctilucent clouds

When it is winter in the Central European part of Russia and most days are gray, dank and cloudy, residents of Scandinavian countries, as well as Kola Peninsula, throughout the second half of January, from time to time they witness a very beautiful and rare natural phenomenon - the appearance of mother-of-pearl clouds in the sky. These clouds appear at an altitude of 22-30 km in cold areas of the stratosphere, where the temperature is below –78° C. These clouds have an iridescent, pearlescent color. This color range is produced by small crystals of water and nitric acid of approximately the same size, which make up the cloud and refract the sun's rays. Research on nacreous clouds is very difficult, since these clouds appear in the sky very rarely.

As for noctilucent clouds, scientists first noticed them in 1885, when they were observed in large numbers over all of Europe. In shape they resembled ordinary cirrus clouds, however, unlike the latter, they were located at altitudes from 75 to 90 kilometers. Subsequently, it was found that such clouds arise in mid-latitudes and most often in the summer at the lower boundary of the ionosphere. Their more precise address is the mesosphere, or more precisely, the mesopause, where extremely low temperatures are observed, reaching minus 140°C. In the northern hemisphere of the Earth, their visibility period is from May to August. And anyone can observe these beautiful clouds on short summer nights.

Noctilucent clouds are light, transparent clouds (so transparent that the stars can be clearly seen through them) and the highest cloud formations. In addition, noctilucent clouds have their own glow, i.e. always look light against a dark sky.

Long-term studies of noctilucent clouds have shown that these clouds consist of tiny ice crystals. It is very likely that the basis for the formation of these ice crystals are particles meteor dust, penetrating our atmosphere from outer space or formed as a result of the destruction of meteoric particles in the atmosphere. Since, most often, noctilucent clouds were observed after strong, especially catastrophic eruptions, there is a hypothesis that they are caused by volcanic ash. This assumption is supported by the fact that after such large eruptions as the eruption of Krakatoa volcano in 1883, noctilucent clouds appeared most often. Very bright noctilucent clouds and light white nights were observed after the fall of the Tunguska meteorite. However, anthropogenic noctilucent and pearlescent clouds arising as a result of nuclear explosions or work cannot be excluded. jet engines airplanes.

Light (or solar) pole

In English it sounds like “Light pillar”. A solar pillar is a well-studied optical effect, which is a vertical strip of light that stretches upward from the setting or rising sun. This phenomenon is caused by hexagonal flat or columnar ice crystals with nearly horizontal parallel flat surfaces. Hanging in the cold air, these flat crystals, refracting sunlight, are capable of causing a solar column, the appearance of which depends on relative position crystals.

However, not only the Sun can generate paths of light in the sky. Given the same conditions under which light pillars become visible near the Sun, they can be observed near any bright object: the Moon, Venus, Jupiter, and even above street lighting.

A forest of light is a very expressive optical effect that occurs in a frosty haze when a light source is reflected from snowflakes shaped like ice plates. This phenomenon can only be seen when the air temperature is at least -20C. Therefore, the Light Forest is most often observed in northern countries: Finland, Norway. Last year it was observed once in Minsk and once in Sheremetyevo.

Udder clouds

These clouds have a bizarre shape that resembles an udder. At a low altitude of the Sun above the horizon, they can acquire a gray-blue, gray-pink, golden and even reddish color. The appearance of these clouds always foreshadows thunderstorms, and the clouds themselves can be located several kilometers from the source of the thunderstorm. In meteorology, "udder-shaped" clouds are called Mammatus.

Mammatus remain in the sky from a few minutes to several hours, gradually disappearing along with the fading thunderstorm.

In the United States, the appearance of Mammatus was previously associated with the appearance of a tornado, but it is now generally accepted that the appearance of Mammatus does not indicate that a tornado or tornado is about to appear. However, thunderstorms that generate Mammatus ensembles are characterized by a high probability of the occurrence of ball lightning, as well as wind shear. However, the appearance of Mammatus in the sky foreshadows that the most powerful and dangerous part of the storm has already passed.

Mammatus can also be observed in the middle latitudes of Russia, but quite rarely. They usually occur during fading thunderstorms. It is the fact that these clouds are formed by downward air movements that makes them unique, because as is known, cloudiness is formed by ascending air currents.

Appear as slender, horizontal spiral curls and look simply drawn . E one of the rarest in nature cloud formations . The duration of their “life” is equal to one or two minutes, which is why seeing them with your own eyes is amazing. great luck. Formed at an altitude of approximately 5000 meters .)