The Earth revolves around the Sun at an average speed of 29.76 km/sec. It travels the entire orbital path in 365 days, 6 hours, 9 minutes, 9.6 seconds.
The most important consequence of the Earth's revolution around the Sun with an almost unchanged position of its axis in space is the change of seasons.
The beginning of astronomical summer in the northern hemisphere - June 22 - summer solstice day. In the southern hemisphere, astronomical winter begins at this time. On the day of the summer solstice, the Earth is at aphelion. The Earth's axis is tilted with its northern end towards the Sun, and the sun's rays at noon fall vertically at latitude 23°27" N - in the northern tropic, June 22, the Sun occupies the highest position of the year in the sky of all latitudes of the northern hemisphere. Latitudes north of 66 °33" s. w. (from the Arctic Circle) find themselves completely on the illuminated half of the Earth (Fig. 14, a), and the Sun does not set below the horizon here.
At all latitudes between the Arctic Circle and the equator, days are longer than nights. The illumination of the northern hemisphere on the day of the summer solstice is the highest of the year. In the southern hemisphere, on the day of the summer solstice, the Sun is especially low above the horizon. South of 66°33" S (from the Antarctic Circle) the polar night reigns, corresponding in duration to the polar day of the same latitudes of the Northern Hemisphere. At all latitudes between the Antarctic Circle and the Equator, the day is shorter than the night. Illumination of the Southern Hemisphere per day the summer solstice is the smallest of the year.

Continuously moving in orbit, on September 23, the Earth takes a position in which the line of light passes through the geographic poles, and day is equal to night throughout the Earth. This autumn equinox. Both hemispheres (northern and southern) are equally illuminated on this day. September 23 is the beginning of astronomical autumn in the northern hemisphere and the beginning of astronomical spring in the southern.
December 22, at winter solstice day, The Earth is at perihelion. The southern hemisphere faces the Sun, and astronomical summer begins there, while astronomical winter begins in the northern hemisphere. At noon, the sun's rays fall vertically on the southern tropic (23°27" S). The area near the south pole, bounded by the Antarctic Circle (66°33" S), is illuminated by the never-setting Sun; The Sun does not rise over the corresponding region in the northern hemisphere. The illumination of the southern hemisphere is the greatest in the year, the northern - the least. Like June 22, day is equal to night only at the equator.

On March 21, the day of the vernal equinox, the Sun illuminates the Earth in the same way as on September 23: it stands at its zenith above the equator, and at all latitudes day is equal to night. It is astronomical spring in the northern hemisphere, and autumn in the southern hemisphere.
The Earth moves in orbit at different speeds. During the period when it is closest to the Sun (at perihelion), its speed of movement is greatest. The lowest speed occurs when the Earth passes through aphelion. It follows that of all the seasons in the northern hemisphere, the longest is summer, and the shortest is winter; in the southern hemisphere, it’s the other way around. The differences in the length of the seasons are small. Currently, spring in the northern hemisphere lasts 92.8 days, summer - 93.6, autumn - 89.8, winter - 89.0.

The Earth is a cosmic object involved in the continuous movement of the Universe. It rotates around its axis, travels millions of kilometers in orbit around the Sun, and, together with the entire planetary system, slowly circles the center of the Milky Way galaxy. The first two movements of the Earth are clearly noticeable to its inhabitants by changes in daily and seasonal illumination, changes in temperature conditions, and characteristics of the seasons. Today our focus is on the characteristics and period of the Earth’s revolution around the Sun, its influence on the life of the planet.

General information

Our planet moves in the third orbit farthest from the star. On average, the Earth is separated from the Sun by 149.5 million kilometers. The orbital length is approximately 940 million km. The planet covers this distance in 365 days and 6 hours (one sidereal, or sidereal, year - the period of revolution of the Earth around the Sun relative to distant luminaries). Its speed during orbital movement reaches an average of 30 km/s.

For an observer on earth, the revolution of a planet around a star is expressed in a change in the position of the Sun in the sky. It moves one degree per day eastward relative to the stars.

Orbit of planet Earth

The trajectory of our planet is not a perfect circle. It is an ellipse with the Sun at one of its focuses. This form of orbit “forces” the Earth to either approach the star or move away from it. The point at which the distance from the planet to the Sun is minimal is called perihelion. Aphelion is the part of the orbit where the Earth is as far away from the star as possible. In our time, the first point is reached by the planet around January 3, and the second on July 4. At the same time, the Earth does not move around the Sun at a constant speed: after passing aphelion, it accelerates and slows down, having overcome perihelion.

The minimum distance separating two cosmic bodies in January is 147 million km, the maximum is 152 million km.

Satellite

Together with the Earth, the Moon also moves around the Sun. When observed from the north pole, the satellite moves counterclockwise. The Earth's orbit and the Moon's orbit lie in different planes. The angle between them is approximately 5º. This discrepancy significantly reduces the number of lunar and solar eclipses. If the orbital planes were identical, then one of these phenomena would occur once every two weeks.

The Earth's orbit is designed in such a way that both objects rotate around a common center of mass with a period of approximately 27.3 days. At the same time, the tidal forces of the satellite gradually slow down the movement of our planet around its axis, thereby slightly increasing the length of the day.

Consequences

The axis of our planet is not perpendicular to the plane of its orbit. This tilt, as well as the movement around the star, leads to certain climate changes throughout the year. The sun rises higher above the territory of our country at a time when the planet’s north pole is inclined towards it. The days are getting longer, the temperature is rising. When it deviates from the luminary, the warmth is replaced by cooling. Similar climate changes are characteristic of the southern hemisphere.

The change of seasons occurs at the points of equinox and solstices, which characterize a certain position of the earth's axis relative to the orbit. Let's look at this in more detail.

The longest and shortest day

Solstice is the moment in time when the planetary axis is maximally inclined towards the star or in the opposite direction. The Earth's orbit around the Sun has two such sections. In mid-latitudes, the point at which the sun appears at noon rises higher every day. This continues until the summer solstice, which falls on June 21 in the northern hemisphere. Then the location of the midday star begins to decrease until December 21-22. These days are the winter solstice in the northern hemisphere. In mid-latitudes, the shortest day arrives, and then it begins to increase. In the southern hemisphere, the axis tilt is opposite, so it falls here in June, and summer in December.

Day equals night

Equinox is the moment when the planet's axis becomes perpendicular to the orbital plane. At this time, the terminator, the boundary between the illuminated and dark half, runs strictly along the poles, that is, day is equal to night. There are also two such points in orbit. The spring equinox falls on March 20, the autumn equinox on September 23. These dates are valid for the northern hemisphere. In the southern one, similar to the solstices, the equinoxes change places: autumn is in March, and spring is in September.

Where is it warmer?

The circular orbit of the Earth - its features combined with the tilt of its axis - has another consequence. At the moment when the planet passes closest to the Sun, the south pole faces in its direction. It is summer in the corresponding hemisphere at this time. The planet at the moment of passing perihelion receives 6.9% more energy than when it passes aphelion. This difference occurs specifically in the southern hemisphere. During the year it receives slightly more solar heat than the northern one. However, this difference is insignificant, since a significant part of the “additional” energy falls on the water expanses of the southern hemisphere and is absorbed by them.

Tropical and sidereal year

The period of revolution of the Earth around the Sun relative to the stars, as already mentioned, is approximately 365 days 6 hours 9 minutes. This is a sidereal year. It is logical to assume that the change of seasons fits into this period. However, this is not entirely true: the time of the Earth’s revolution around the Sun does not coincide with the full period of the seasons. It makes up the so-called tropical year, lasting 365 days, 5 hours and 51 minutes. It is most often measured from one vernal equinox to the next. The reason for the twenty-minute difference between the duration of the two periods is the precession of the earth's axis.

Calendar year

For convenience, it is generally accepted that there are 365 days in a year. The remaining six and a half hours add up to a day during four revolutions of the Earth around the Sun. To compensate for this and in order to prevent the difference between the calendar and sidereal years from increasing, an “extra” day is introduced, February 29.

The Earth's only satellite, the Moon, has some influence on this process. It is expressed, as noted earlier, in the slowing down of the planet’s rotation. Every hundred years, the length of the day increases by about one thousandth.

Gregorian calendar

The counting of days we are accustomed to was introduced in 1582. unlike the Julian, over a long period of time allows the “civil” year to correspond to the full cycle of seasons. According to it, months, days of the week and dates are exactly repeated every four hundred years. The length of the year in the Gregorian calendar is very close to the tropical one.

The purpose of the reform was to return the day of the vernal equinox to its usual place - on March 21. The fact is that from the first century AD to the sixteenth century, the real date when day is equal to night moved to March 10. The main motivation for revising the calendar was the need to correctly calculate the day of Easter. To achieve this, it was important to keep March 21 a day close to the real equinox. The Gregorian calendar copes with this task very well. The date of the vernal equinox will shift by one day no earlier than in 10,000 years.

If we compare the calendar, more significant changes are possible here. As a result of the peculiarities of the Earth's movement and the factors influencing it, over approximately 3,200 years, a discrepancy with the change of seasons of one day will accumulate. If at this time it is important to maintain the approximate equality of the tropical and calendar years, then a reform similar to that carried out in the 16th century will again be required.

The period of revolution of the Earth around the Sun thus correlates with the concepts of calendar, sidereal and tropical years. Methods for determining their duration have been improved since antiquity. New data on the interaction of objects in outer space allow us to make assumptions about the relevance of the modern understanding of the term “year” in two, three and even ten thousand years. The time of the Earth's revolution around the Sun and its connection with the change of seasons and the calendar is a good example of the influence of global astronomical processes on human social life, as well as the dependencies of individual elements within the global system of the Universe.

Like other planets of the solar system, it makes 2 main movements: around its own axis and around the Sun. Since ancient times, it was on these two regular movements that time calculations and the ability to compile calendars were based.

A day is the time of rotation around its own axis. A year is a revolution around the Sun. The division into months is also in direct connection with astronomical phenomena - their duration is related to the phases of the Moon.

Rotation of the Earth around its own axis

Our planet rotates around its own axis from west to east, that is, counterclockwise (when viewed from the North Pole.) An axis is a virtual straight line crossing the globe in the area of ​​the North and South Poles, i.e. the poles have a fixed position and do not participate in rotational motion, while all other location points on the earth's surface rotate, and the rotation speed is not identical and depends on their position relative to the equator - the closer to the equator, the higher the rotation speed.

For example, in the Italian region the rotation speed is approximately 1200 km/h. The consequences of the Earth's rotation around its axis are the change of day and night and the apparent movement of the celestial sphere.

Indeed, it seems that the stars and other celestial bodies of the night sky are moving in the opposite direction to our movement with the planet (that is, from east to west).

It seems that the stars are around the North Star, which is located on an imaginary line - a continuation of the earth's axis in a northerly direction. The movement of stars is not proof that the Earth rotates around its axis, because this movement could be a consequence of the rotation of the celestial sphere, if we assume that the planet occupies a fixed, motionless position in space.

Foucault pendulum

Irrefutable proof that the Earth rotates on its own axis was presented in 1851 by Foucault, who conducted the famous experiment with a pendulum.

Let's imagine that, being at the North Pole, we set a pendulum into oscillatory motion. The external force acting on the pendulum is gravity, but it does not affect the change in the direction of oscillations. If we prepare a virtual pendulum that leaves marks on the surface, we can make sure that after some time the marks will move in a clockwise direction.

This rotation can be associated with two factors: either with the rotation of the plane on which the pendulum makes oscillatory movements, or with the rotation of the entire surface.

The first hypothesis can be rejected, taking into account that there are no forces on the pendulum that can change the plane of oscillatory movements. It follows that it is the Earth that rotates, and it makes movements around its own axis. This experiment was carried out in Paris by Foucault, he used a huge pendulum in the form of a bronze sphere weighing about 30 kg, suspended from a 67-meter cable. The starting point of the oscillatory movements was recorded on the surface of the floor of the Pantheon.

So, it is the Earth that rotates, and not the celestial sphere. People observing the sky from our planet record the movement of both the Sun and planets, i.e. All objects in the Universe move.

Time criterion – day

A day is the period of time during which the Earth makes a complete revolution around its own axis. There are two definitions of the concept “day”. A “solar day” is a period of time of the Earth’s rotation, during which . Another concept - “sidereal day” - implies a different starting point - any star. The duration of the two types of days is not identical. The length of a sidereal day is 23 hours 56 minutes 4 seconds, while the length of a solar day is 24 hours.

The different durations are due to the fact that the Earth, rotating around its own axis, also performs an orbital rotation around the Sun.

In principle, the length of a solar day (although it is taken as 24 hours) is not a constant value. This is due to the fact that the Earth's orbital movement occurs at a variable speed. When the Earth is closer to the Sun, its orbital speed is higher; as it moves away from the sun, the speed decreases. In this regard, such a concept as “average solar day” was introduced, namely its duration is 24 hours.

Orbiting the Sun at a speed of 107,000 km/h

The speed of the Earth's revolution around the Sun is the second main movement of our planet. The Earth moves in an elliptical orbit, i.e. the orbit has the shape of an ellipse. When it is in close proximity to the Earth and falls into its shadow, eclipses occur. The average distance between the Earth and the Sun is approximately 150 million kilometers. Astronomy uses a unit to measure distances within the solar system; it is called the “astronomical unit” (AU).

The speed at which the Earth moves in orbit is approximately 107,000 km/h.
The angle formed by the earth's axis and the plane of the ellipse is approximately 66°33', this is a constant value.

If you observe the Sun from Earth, you get the impression that it is the Sun that moves across the sky throughout the year, passing through the stars and stars that make up the Zodiac. In fact, the Sun also passes through the constellation Ophiuchus, but it does not belong to the Zodiac circle.

Like other planets, the Earth in its orbit revolves around the Sun along a closed circle. But the Earth's orbit is not a regular circle, but a slightly elongated circle. Therefore, once a year the Earth comes close to the Sun (January 3) and once moves away from it to the farthest point of its orbit (July 5). The difference between the closest location of the Earth from the Sun (147 million km) and the farthest (152 million km) is only 2 million km. This, compared to the average distance from the Earth to the Sun, is a very small value. The Earth completes its orbit around the Sun in 365 days and 6 hours. It is generally accepted that there are 365 days in a year. The remaining 6 hours add up to 24 hours (or one day) over 4 years. These days are added every 4 years to February. Then 3 years consist of 365 days (in February - 28 days), and the 4th year - of 366 days (in February - 29 days). Years even to the 4th and consisting of 366 days are called leap years.

23. Earth's gravitational field. Geomagnetic field of the Earth.

GRAVITATIONAL FIELD OF THE EARTH (a. gravitational field of the Earth, Earth gravitational field; n. Schwerefeld der Erde; f. champ de gravite de la Terre; i. campo de gravedad de la tierra) - a force field caused by the attraction of the Earth’s masses and centrifugal the force that arises as a result of the daily rotation of the Earth; also slightly depends on the attraction of the Moon and the Sun and other celestial bodies and the masses of the earth’s atmosphere. The Earth's gravitational field is characterized by gravity, gravity potential and its various derivatives. The potential has the dimension m2 s-2, the unit of measurement for the first derivatives of the potential (including gravity) in gravimetry is taken to be milligal (mGal), equal to 10-5 m s-2, and for the second derivatives - etvos (E, E ), equal to 10-9 s-2.

Values ​​of the main characteristics of the Earth's gravitational field: gravity potential at sea level 62636830 m2 s-2; the average gravity on Earth is 979.8 Gal; decrease in average gravity from pole to equator 5200 mGal (including due to the daily rotation of the Earth 3400 mGal); maximum gravity anomaly on Earth 660 mGal; normal vertical gravity gradient 0.3086 mGal/m; the maximum deviation of the plumb line on Earth is 120"; the range of periodic lunar-solar variations in gravity is 0.4 mGal; the possible value of the secular change in gravity<0,01 мГал/год.

The part of the gravitational potential due only to the Earth's gravity is called geopotential. To solve many global problems (studying the figure of the Earth, calculating satellite trajectories, etc.), the geopotential is presented in the form of an expansion into spherical functions. The second derivatives of the gravitational potential are measured by gravity gradiometers and variometers. There are several expansions of geopotential, differing in the initial observational data and degrees of expansion.

Usually the Earth's gravitational field is represented as consisting of 2 parts: normal and anomalous. The main - normal part of the field corresponds to a schematized model of the Earth in the form of an ellipsoid of rotation (normal Earth). It is consistent with the real Earth (the centers of mass, mass values, angular velocities and daily rotation axes coincide).

We now know that the geomagnetic field has existed for at least 3.5 billion years, and during this time the magnetic poles have swapped places thousands of times (Brunhes and Matuyama studied the most recent reversal, which now bears their names). Sometimes the geomagnetic field maintains its orientation for tens of millions of years, and sometimes for no more than five hundred centuries. The inversion process itself usually takes several thousand years, and upon completion, the field strength, as a rule, does not return to its previous value, but changes by several percent.

How many magnetic poles do you think our planet has? Almost everyone will say that two are in the Arctic and Antarctic. In fact, the answer depends on the definition of the concept of pole. Geographic poles are considered to be the points of intersection of the earth's axis with the surface of the planet. Since the Earth rotates as a rigid body, there are only two such points and nothing else can be thought of. But with magnetic poles the situation is much more complicated. For example, a pole can be considered a small area (ideally, again a point) where the magnetic lines of force are perpendicular to the earth's surface. However, any magnetometer records not only the planetary magnetic field, but also the fields of local rocks, electric currents of the ionosphere, solar wind particles and other additional sources of magnetism (and their average share is not so small, on the order of several percent). The more accurate the device, the better it does this - and therefore makes it increasingly difficult to isolate the true geomagnetic field (it is called the main one), the source of which is located in the depths of the earth. Therefore, pole coordinates determined by direct measurement are not stable even over a short period of time.

You can act differently and establish the position of the pole on the basis of certain models of terrestrial magnetism. To a first approximation, our planet can be considered a geocentric magnetic dipole, the axis of which passes through its center. Currently, the angle between it and the earth's axis is 10 degrees (several decades ago it was more than 11 degrees). With more accurate modeling, it turns out that the dipole axis is shifted relative to the center of the Earth towards the northwestern part of the Pacific Ocean by about 540 km (this is an eccentric dipole). There are other definitions.

But that's not all. The Earth's magnetic field actually does not have dipole symmetry and therefore has multiple poles, and in huge numbers. If we consider the Earth to be a magnetic quadrupole, a quadrupole, we will have to introduce two more poles - in Malaysia and in the southern part of the Atlantic Ocean. The octupole model specifies the eight poles, etc. The modern most advanced models of terrestrial magnetism operate with as many as 168 poles. It is worth noting that during the inversion, only the dipole component of the geomagnetic field temporarily disappears, while the others change much less.

Where does the Earth's magnetic field even come from? One possible explanation is simply glaring. The Earth has an inner solid iron-nickel core, the radius of which is 1220 km. Since these metals are ferromagnetic, why not assume that the inner core has static magnetization, which ensures the existence of the geomagnetic field? The multipolarity of terrestrial magnetism can be attributed to the asymmetry of the distribution of magnetic domains inside the core. Pole migration and geomagnetic field reversals are more difficult to explain, but we can probably try.

24. Clouds. International classification of clouds. Condensation and sublimation.

Clouds- products of condensation of water vapor suspended in the atmosphere, visible in the sky from the surface of the earth.

Clouds are made up of tiny droplets of water and/or ice crystals (called cloud elements). Drip cloud elements are observed when the air temperature in the cloud is above −10 °C; from −10 to −15 °C clouds have a mixed composition (droplets and crystals), and at temperatures in the cloud below −15 °C they are crystalline.

As cloud elements become larger and their rate of fall increases, they fall out of the clouds in the form of precipitation. As a rule, precipitation falls from clouds that have a mixed composition at least in some layer (cumulonimbus, nimbostratus, altostratus). Light drizzle (in the form of drizzle, snow grains or light fine snow) can fall from clouds of homogeneous composition (drip or crystalline) - stratus, stratocumulus.

UPPER LEVEL CLOUDS(h>6km)
Cirrus clouds(Cirrus, Ci) are individual clouds of a fibrous structure and a whitish hue. Sometimes they have a very regular structure in the form of parallel threads or stripes, sometimes on the contrary, their fibers are tangled and scattered across the sky in separate spots. Cirrus clouds are transparent because they consist of tiny ice crystals. Often the appearance of such clouds heralds a change in the weather. From satellites, cirrus clouds are sometimes difficult to see.

Cirrocumulus clouds(Cirrocumulus, Cc) - a layer of clouds, thin and translucent, like cirrus, but consisting of individual flakes or small balls, and sometimes as if from parallel waves. These clouds usually form, figuratively speaking, a “cumulus” sky. They often appear along with cirrus clouds. Sometimes visible before storms.

Cirrostratus clouds(Cirrostratus, Cs) - a thin, translucent whitish or milky cover, through which the disk of the Sun or Moon is clearly visible. This cover can be uniform, like a layer of fog, or fibrous. On cirrostratus clouds, a characteristic optical phenomenon is observed - a halo (light circles around the Moon or Sun, false Sun, etc.). Like cirrus, cirrostratus clouds often indicate the approach of severe weather.

> MIDDLE LEVEL CLOUDS(h=2-6 km)
They differ from similar lower-level cloud forms in their high altitude, lower density, and greater likelihood of having an ice phase.
Altocumulus clouds(Altocumulus, Ac) - a layer of white or gray clouds consisting of ridges or individual “blocks”, between which the sky is usually visible. The ridges and “blocks” that form the “feathery” sky are relatively thin and are arranged in regular rows or in a checkerboard pattern, less often - in disorder. "Cirrus" skies are usually a sign of pretty bad weather.

Altostratus clouds(Altostratus, As) - a thin, less often dense veil of a grayish or bluish tint, in places heterogeneous or even fibrous in the form of white or gray shreds all over the sky. The Sun or Moon shines through it in the form of light spots, sometimes quite faint. These clouds are a sure sign of light rain.

> LOWER CLOUDS(h<2 км)
According to many scientists, it is illogical to classify nimbostratus clouds as the lower tier, since this tier contains only their bases, and the tops reach a height of several kilometers (middle tier cloud levels). These heights are more typical for clouds of vertical development, and therefore some scientists classify them as middle-tier clouds.

Stratocumulus clouds(Stratocumulus, Sc) - a cloud layer consisting of ridges, shafts or individual elements thereof, large and dense, gray in color. There are almost always darker areas.
The word “cumulus” (from the Latin “heap”, “heap”) means a crowded, piled-up cloud. These clouds rarely bring rain, only sometimes they turn into nimbostratus clouds, from which rain or snow falls.

Stratus clouds(Stratus, St) - a rather homogeneous layer of low gray clouds, devoid of regular structure, very similar to fog that has risen a hundred meters over the ground. Stratus clouds cover large areas and look like torn rags. In winter, these clouds often remain throughout the day; precipitation usually does not fall on the ground; sometimes there is drizzle. In summer they quickly dissipate, after which good weather sets in.

Nimbostratus clouds(Nimbostratus, Ns, Frnb) are dark gray clouds, sometimes threatening in appearance. Often, low dark fragments of broken rain clouds appear below their layer - typical harbingers of rain or snowfall.

> VERTICAL CLOUDS

Cumulus clouds (Cumulus, Cu)- dense, sharply defined, with a flat, relatively dark base and a dome-shaped white, as if swirling, top, reminiscent of cauliflower. They begin in the form of small white fragments, but soon they form a horizontal base, and the cloud begins to rise imperceptibly. With little humidity and weak vertical ascent of air masses, cumulus clouds foretell clear weather. Otherwise, they accumulate throughout the day and can cause a thunderstorm.

Cumulonimbus (Cb)- powerful cloud masses with strong vertical development (up to a height of 14 kilometers), giving heavy rainfall with thunderstorm phenomena. They develop from cumulus clouds, differing from them in the upper part, consisting of ice crystals. These clouds are associated with squally winds, heavy precipitation, thunderstorms, and hail. The lifespan of these clouds is short - up to four hours. The base of the clouds is dark in color, and the white top goes far above. In the warm season, the peak can reach the tropopause, and in the cold season, when convection is suppressed, the clouds are flatter. Usually clouds do not form a continuous cover. When a cold front passes, cumulonimbus clouds can form a swell. The sun does not shine through the cumulonimbus clouds. Cumulonimbus clouds are formed when the air mass is unstable, when active upward movement of air occurs. These clouds also often form on a cold front when cold air hits a warm surface.

Each genus of clouds, in turn, is divided into species according to the characteristics of their shape and internal structure, for example, fibratus (fibrous), uncinus (claw-shaped), spissatus (dense), castellanus (tower-shaped), floccus (flaky), stratiformis (stratified). ), nebulosus (foggy), lenticularis (lenticular), fractus (torn), humulus (flat), mediocris (medium), congestus (powerful), calvus (bald), capillatus (hairy). Types of clouds, further, have varieties, for example, vertebratus (ridge-shaped), undulatus (wavy), translucidus (translucent), opacus (non-translucent), etc. Further, additional features of clouds are distinguished, such as incus (anvil), mamma (snake-shaped) , vigra (fall stripes), tuba (trunk), etc. And finally, evolutionary features indicating the origin of clouds are noted, for example, Cirrocumulogenitus, Altostratogenitus, etc.

When observing cloudiness, it is important to determine by eye the degree of sky coverage on a ten-point scale. Clear sky - 0 points. It's clear, there are no clouds in the sky. If the sky is covered with clouds no more than 3 points, partly cloudy. Partly cloudy 4 points. This means that clouds cover half the sky, but at times their amount decreases to "clear". When the sky is half covered, cloudiness is 5 points. If they say “sky with gaps,” they mean that the cloudiness is at least 5, but not more than 9 points. Cloudy - the sky is completely covered with clouds of a single blue sky. Cloud cover 10 points.

Condensation vapors (lat. condense- compact, thicken) - the transition of a substance into a liquid or solid state from a gaseous state.

Sublimation (sublimation) - the transition of a substance from a solid state directly to a gaseous state, bypassing the liquid state.

25. Formation of precipitation. Characteristics of precipitation regime.

Atmospheric precipitation- water in a liquid or solid state that falls from clouds or settles from the air onto the earth's surface.

Rain

Under certain conditions, cloud droplets begin to merge into larger and heavier ones. They can no longer stay in the atmosphere and fall to the ground in the form rain.

hail

It happens that in summer the air quickly rises, picks up rain clouds and carries them to a height where the temperature is below 0°. Raindrops freeze and fall as hail(Fig. 1).

Rice. 1. Origin of the hail

Snow

In winter, in temperate and high latitudes, precipitation falls in the form of snow. Clouds at this time do not consist of water droplets, but of tiny crystals - needles, which, when combined together, form snowflakes.

The mysterious and magical world of astronomy has attracted the attention of mankind since ancient times. People raised their heads up to the starry sky and asked eternal questions about why the stars change their position, why day and night come, why somewhere a blizzard howls, and somewhere in the desert it’s plus 50...

Movement of the luminaries and calendars

Most of the planets in the solar system revolve around themselves. At the same time, they all make revolutions around the Sun. Some do it quickly and swiftly, others slowly and solemnly. Planet Earth is no exception; it is constantly moving in outer space. Even in ancient times, people, not knowing the reasons and mechanism of this movement, noticed a certain general pattern and began to compile calendars. Even then, humanity was interested in the question of what speed the Earth revolves around the Sun.

The sun rises at sunrise

The movement of the Earth around its axis is the Earth's day. And the complete passage of our planet in an ellipsoidal orbit around the star is a calendar year.

If you stand at the North Pole and draw an imaginary axis through the Earth to the South Pole, it turns out that our planet is moving from west to east. Remember, back in “The Tale of Igor’s Campaign” it is said that “The sun rises at sunrise”? The East always receives the sun's rays before the West. That is why the New Year begins earlier in the Far East than in Moscow.

At the same time, scientists have determined that only two points on our planet are in a static position relative to the North and South Poles.

Crazy speed

All other places on the planet are in perpetual motion. What is the speed of the Earth's revolution around the Sun? At the equator it is highest and reaches 1670 km per hour. Closer to mid-latitudes, for example, in Italy, the speed is already much lower - 1200 km per hour. And the closer to the poles, the smaller and smaller it is.

The period of rotation of the Earth around its axis is 24 hours. That's what scientists say. We call it simpler - a day.

At what speed does the Earth rotate around the Sun?

350 times faster than a racing car

In addition to rotating around its axis, the Earth also makes an elliptical motion around a star called the Sun. At what speed Scientists have long calculated this indicator using complex formulas and calculations. The speed of the Earth's revolution around the Sun is 107 thousand kilometers per hour.

It's hard to even try to imagine these crazy, unrealistic numbers. For example, even the most racing car - 300 kilometers per hour - is 356 times less than the speed of the Earth in orbit.

It seems to us that it is rising and rising, that the Earth is motionless, and the luminary is making a circle in the sky. For a very long time, humanity thought exactly this way, until scientists proved that everything happens the other way around. Today, even a schoolchild knows what is happening in the world: the planets move smoothly and solemnly around the Sun, and not the other way around. The Earth revolves around the Sun, and not at all as ancient people previously believed.

So, we found out that the rotation speed of the earth around its axis and the Sun is 1670 km per hour (at the equator) and 107 thousand kilometers per hour, respectively. Wow, we're flying!

Solar and sidereal year

A full circle, or rather an ellipsoidal oval, the planet Earth goes around the Sun in 356 days 5 hours 48 minutes 46 seconds. Astronomers call these numbers the “astrological year.” Therefore, to the question “What is the frequency of the Earth’s revolution around the Sun?” we answer simply and succinctly: “A year.” This indicator remains unchanged, but for some reason, every four years we have a leap year, in which there is one more day.

It’s just that astronomers have long agreed that the extra 5 and “kopecks” hours are not counted every year, but have chosen the number of the astronomical year, which is a multiple of the day. Thus, a year is 365 days. But so that over time there is no failure, so that natural rhythms do not shift in time, once every four years a single extra day appears in the calendar in February. Over the course of 4 years, these quarter days “gather” into a full day - and we celebrate a leap year. Thus, answering the question about what is the frequency of the Earth’s revolution around the Sun, feel free to say one year.

In the scientific world there are the concepts of “solar year” and “sidereal (sidereal) year.” The difference between them is approximately 20 minutes and it occurs due to the fact that our planet moves faster in its orbit than the Sun returns to the place that astronomers have determined as the point of the vernal equinox. We already know the speed of the Earth's revolution around the Sun, and the full period of the Earth's revolution around the Sun is 1 year.

Days and years on other planets

The nine planets of the solar system have their own “concepts” about speed, what a day is and what an astronomical year is.

The planet Venus, for example, revolves around itself in 243 Earth days. Can you imagine how much you can do there in one day? And how long does the night last?

But on Jupiter the opposite is true. This planet spins around its axis at a gigantic speed and manages to rotate 360 ​​degrees in 9.92 hours.

The Earth's orbital speed around the Sun is a year (365 days), but Mercury's is only 58.6 Earth days. On Mars, the closest planet to Earth, the day lasts almost as long as on Earth - 24 and a half hours, but the year is almost twice as long - 687 days.

The Earth's revolution around the Sun is 365 days. Now let's multiply this figure by 247.7 and get one year on the planet Pluto. A millennium has passed for us, but only four years have passed on the farthest planet in the solar system.

These are paradoxical values ​​and numbers that are frightening in their scale.

Mysterious ellipse

To understand why the seasons periodically change on planet Earth, why it is cold here in the middle zone in winter, it is important not only to answer the question of how fast the Earth rotates around the Sun, and along what path. It is also necessary to understand how it does this.

And she does this not in a circle, but in an ellipse. If we draw the Earth's orbit around the Sun, we will see that it is closest to the luminary in January, and farthest in July. The closest point in the Earth's orbit is called perihelion, and the farthest point is called aphelion.

Since the earth's axis is not in a strictly vertical position, but is tilted by approximately 23.4 degrees, and in relation to the ellipsoidal orbit the angle of inclination increases to 66.3 degrees, it turns out that in different positions the Earth exposes different sides to the Sun.

Due to the inclination of the orbit, the Earth turns towards the star in different hemispheres, hence the change in weather. When winter rages in the Northern Hemisphere, hot summer blooms in the Southern Hemisphere. Six months will pass and the situation will change exactly the opposite.

Spin, earthly luminary!

Does the Sun revolve around anything? Of course yes! There are no absolutely motionless objects in space. All the planets, all their satellites, all comets and asteroids are spinning like clockwork. Of course, different celestial bodies have different rotation speeds and axis tilt angles, but they are still always in motion. And the Sun, which is a star, is no exception.

The solar system is not an independent closed space. It is part of a huge spiral galaxy called the Milky Way. It, in turn, includes no less than another 200 billion stars. The sun moves in a circle relative to the center of this galaxy. Scientists also calculated the speed of rotation of the Sun around the axis and the Milky Way galaxy using long-term observations and mathematical formulas.

Today such data is available. The Sun completes its full cycle of circular motion around the Milky Way in 226 million years. In astronomical science, this figure is called the “galactic year.” Moreover, if we imagine the surface of the galaxy as flat, then our star makes slight oscillations, up and down, alternately appearing in the Northern and Southern hemispheres of the Milky Way. The frequency of such fluctuations is 30-35 million years.

Scientists believe that the Sun managed to make 30 full revolutions around the Milky Way during the existence of the Galaxy. Thus, the Sun has lived only 30 galactic years so far. In any case, that's what scientists say.

Most scientists believe that life on Earth began 252 million years ago. Thus, it can be argued that the first living organisms on Earth appeared when the Sun made its 29th revolution around the Milky Way, that is, in the 29th year of its galactic life.

The body and gases move at different speeds

We learned a lot of interesting facts. We already know the rate of revolution of the Earth around the Sun, we have found out what the astronomical and galactic year are, at what speed the Earth and the Sun move in their orbits, and now we will determine at what speed the Sun rotates around its axis.

The fact that the Sun rotates was noticed by ancient researchers. Similar spots periodically appeared and disappeared on it, which led to the conclusion that it rotated around an axis. But at what speed? Scientists, having the most modern research methods, argued about this for a very long time.

After all, our star has a very complex composition. His body is a solid liquid. Inside there is a solid core, around which a hot liquid mantle is located. Above it is a hard crust. Plus, the surface of the Sun is shrouded in hot gas, which constantly burns. It is a heavy gas that consists mainly of hydrogen.

So, the body of the Sun itself rotates slowly, but this burning gas rotates quickly.

25 days and 22 years

The outer shell of the Sun makes a complete rotation around its axis in 27 and a half days. Astronomers were able to determine this by observing sunspots. But this is the average. For example, at the equator they rotate faster and rotate around their axis in 25 days. At the poles, the spots move at a speed of 31 to 36 days.

The body of the star itself rotates around its axis in 22.14 years. In general, over a hundred years of earthly life, the Sun will turn around its axis only four and a half times.

Why do scientists study the rotation speed of our star so accurately?

Because it provides answers to many evolutionary questions. After all, the Sun star is the source of life for all life on Earth. It was because of solar flares, as many researchers believe, that life appeared on Earth (252 million years ago). And it was precisely because of the behavior of the Sun that dinosaurs and other reptiles died in ancient times.

Shine brightly on us, Sun!

People constantly wonder whether the Sun will exhaust its energy and go out? Of course, it will go out - nothing is eternal in the world. And for such massive stars there is a time of birth, activity and decay. But for now the Sun is in the middle of the evolutionary cycle and it has enough energy. By the way, at the very beginning this star was less bright. Astronomers have determined that in the earliest stages of development, the brightness of the Sun was 70 percent lower than it is now.