- one of the amazing phenomena of our planet, which can usually be seen in the northern latitudes. But sometimes it can be seen even in London or Florida. Moreover, the northern lights can be seen even in the very south of the Earth - in Antarctica. This phenomenon also occurs on other planets of the solar system: Mars, Jupiter, Venus.
Northern Lights: what is it
Northern lights (polar lights or aurora) - luminescence (glow) in the upper atmosphere of planet Earth. These layers have a magnetosphere due to their interaction with the charged particles of the solar wind.
The northern lights are thousands of multi-colored lights that light up in the sky on dark nights. Lights come in a variety of shapes and colors: blue, yellow, red, green. In a second, the dark sky is painted in bright colors and becomes visible around for many kilometers as if during the day. The northern or polar lights have been surprising and captivating people for thousands of years, but not everyone treats it with admiration; in the legends of some peoples, which we will discuss below, it was considered a bad sign.
Northern Lights: what is it and how does it happen
Let's see what is this northern lights that surprises and frightens people living near the north and south poles?
Mikhail Lomonosov guessed the mystery of the mysterious lights, deciding that electricity plays a role here. To confirm his theory, the scientist passed a current through flasks filled with various gases. After the experiment, the flasks shone with unique colors.
Simply put, charged particles thrown out by our Sun (solar wind) cause the Earth's air to shimmer with colorful lights.
The earth is a magnet for particles, which generates magnetic fields due to the currents generated during the rotation of the core, which is based on iron. With the help of magnetic attraction, our planet "catches" the passing solar wind and directs it to where the magnetic poles are. There, solar particles are instantly attracted to them, and from the collision of the solar wind with the atmosphere, energy appears that is converted into light, which forms the northern lights.
Excited atoms calm down and begin to emit a light photophone;
If nitrogen (N), colliding with solar particles, loses electrons, then its molecules will be converted into blue and violet colors;
If the electron does not disappear anywhere, then red rays appear;
When the solar wind interacts with oxygen (O), the electron does not disappear, but begins to emit rays of green and red colors.
Northern Lights: Legends
Since ancient times, the northern lights have been associated with various mysterious and sometimes even mystical events. Some peoples believed that heavenly fire brings happiness, supposedly the gods have holidays at this time. Others believed that the god of fire was very angry and troubles should be expected. Let's listen to what the legends of different nations say about the northern lights.
The Norwegians mention a shimmering bridge that appears from time to time in the firmament for the gods to come down to earth. Some called the radiance the fires in the hands of the Valkyries, whose armor is polished to a shine and an amazing radiance arises from them. Others said that the lights are the dance of the souls of dead girls.
In the stories of the ancient Finns, the aurora borealis means the river Ruža burning with fire, which separates the world of the dead and the world of the living.
North American Eskimos believe that you can make the sky sparkle with colorful lights by whistling, and by clapping your hands you can immediately extinguish them.
The Eskimos of Alaska claim that the Northern Lights bring disaster. Before going outside, in the old days they took weapons for protection. Many believed that if you watch the lights for a long time, you can go crazy.
There is every reason to believe that it was thanks to the radiance that myths about dragons arose. Many scientists believe that the battle of St. George, who patronizes all the British, is not connected with a terrible snake, but with the aurora borealis!
When can you see the Northern Lights
Those who want to know for sure when you can see the northern lights should read this paragraph carefully. It can be seen on a clear, frosty night, with an incomplete moon, preferably away from the city (so that the light of the lanterns does not interfere). Aurora Borealis appears mainly from October to January and occurs at an altitude of 80 to 1000 kilometers above sea level and lasts from 1 hour to a whole day.
The more aggressive the Sun behaves, the more explosions occur on it, the longer the aurora lasts. The most beautiful flashes can be seen once every 11 years (such is the cyclicity of the Sun).
Northern lights, photo which is always spectacular, somewhat reminiscent of a sunset (only at night), but can also be embodied in the form of spirals or arcs. The width of the colored ribbon may well exceed 160 km, the length - 1500 km.
The very color of the aurora depends largely on what gas the solar wind interacts with, but also on the altitude where it happened. If the gases of the atmosphere collide at an altitude of more than 150 km, the color of the glow will be red, from 120 to 150 km - yellow-green, below 120 km - violet-blue. More often, the northern lights are pale green.
The footage received from space confirmed the version that the aurora from the south side of the globe almost mirrors this phenomenon from the north side. It is a ring with a diameter of 4000 km, which encircle the poles.
Where can you see the Northern Lights?
It was possible to see the aurora in the Middle Ages, when the north magnetic pole was to the east, not only in Scandinavia or in the north of Russia, but even in the north of China.
Now you can see the northern lights near the magnetic poles of our planet:
at the north pole (it is clearly visible on the Ross Basin);
in ;
in North America (from 20 to 200 times a year);
in the north of the Scandinavian countries, especially on the island of Svalbard. Here you can observe it no less than in North America;
in latitudes between London and Paris - 5-10 times a year;
in northern Florida, the northern lights occur four times a year;
c - on the Kola Peninsula;
in Scotland (and in April);
from space (when there is no influence of the lower dense layers of the atmosphere, which significantly distort the spectacle).
You can see the northern lights on other planets of the solar system - on Jupiter, Venus, Mars, and possibly on Saturn.
So far, all the mysteries of flickering lights have not yet been solved. Scientists are especially interested in the question of whether it is accompanied by a sound effect.
The first work on cloudiness was carried out by Acad. Wild in the early 70s of the XIX century. Since until the 1970s cloudiness was recorded in words and not in numbers, the accuracy of such definitions is low. The second work was written by Voeikov, who used a 10-point system to assess cloudiness, but there were still few observations to characterize the cloudiness in detail. In 1895, Shenrock published a paper containing graphs of the annual course of cloudiness, as well as a map of the distribution of cloudiness by season and for the year. Later, he gave a cloud distribution map (1900) based on more complete data. In 1925, in the Atlas of Industry, and later (1939) in the Great Soviet Atlas of the World, cloud maps compiled by E. S. Rubinshtein were printed. In previous works, data on cloudiness for one period were not presented. This was done in the last work of E. S. Rubinshtein, although the possibility of such a reduction was pointed out earlier by Konrad.
Sunshine was studied by Figurovsky (1897) and Vannari (1907-1909). There are no later works characterizing the distribution of sunshine and cloudiness in the USSR.
ANNUAL CLOUD COVERAGE
There are four main types of annual cloud cover in the USSR.
Type I, Eastern European, with a maximum of cloudiness in winter and a minimum in summer, is observed approximately between the 60th and 42nd parallels and from the western borders of the USSR to the 70° meridian. To the east of the Sea of Azov, the maximum cloudiness occurs in December, on the northern coast of the Black Sea (Odessa, Taganrog) and in Turkmenistan - in January; in Crimea - in February. A large amplitude of cloudiness is observed throughout the region.
Type II, East Siberian, is characterized by a maximum of cloudiness in the summer half of the year, a minimum - in winter. This type is observed in the East Siberian and Far Eastern regions. Here everywhere the clearest month is January or February. The time of the onset of the maximum varies within very large limits: from May to August. So, in the lower reaches of the Amur, the maximum is observed in May; on the middle currents, in Blagoveshchensk - in June; on the upper reaches, in Nerchinsk, the maxima (slightly prominent) are in May and August.
Type III, transitional, with minimum and maximum cloudiness in transitional seasons, is characteristic of the rest of the territory of the USSR (excluding mountain ranges), i.e., for the West Siberian region (between 60 and 90 longitudes and from 50 to 67 ° N) , the Far North, as well as for Bessarabia and the Black Sea coast of the Caucasus.
Type IV, alpine, has a minimum of cloudiness in winter and a maximum in May or June. Low cloudiness in the mountains in winter is explained by the fact that at this time of the year predominantly low stratus clouds are formed that do not reach the tops of the mountains (the Greater and Lesser Caucasus, the mountains of Central Asia, Altai).
The amplitude of the annual variation of cloudiness, as a rule, increases in the direction from the coasts to the interior of the continent, while the average cloudiness decreases in the same direction.
The daily course of cloudiness in the warm half-year in the European part of the USSR has two maxima: one at night (due to stratus clouds under appropriate types of weather), the other during the day (due to the formation of clouds due to ascending currents); in the cold half-year, only one maximum is usually observed (at night or in the morning). In the Asian part of the USSR, there is mainly one maximum of cloudiness - in summer in the daytime, in winter in the morning.
In the mountainous regions of the country, the daytime maximum of cloudiness is clearly expressed in summer, while in winter it is nighttime.
CLOUD DISTRIBUTION
According to Brooks' calculations, the average cloudiness is distributed as follows depending on latitude (for the northern hemisphere):
In the USSR, the greatest cloud cover is observed over the Arctic and the White Sea (latitude about 70°), where it averages 88% per year, and 94% in November and December (Sosnovets lighthouse). Towards the south and especially to the southeast, cloudiness decreases, amounting to 35-25% in Turan (latitude 40 ° - 50 °), 50% in the Crimea and Transcaucasia, 35% in Transbaikalia and Central Asia and 35-25% in the Far East. 40%.
In winter, the least cloudiness is observed in Transbaikalia and the East Siberian region (20-35%), which is closely related to high atmospheric pressure and low temperatures.
The winter isonefa in 60% crosses the middle of the Caspian and, touching the western outskirts of the Aral, goes to the Urals. Further, it passes along the eastern slope of the Urals to the mouth of the Ob, and then turns to the southeast and, skirting the Vasyugan swamps, reaches Novosibirsk. Then the isonefa follows the Yenisei to the Kara coast. Thus, on the eastern slope of the Urals and in the central part of the West Siberian Lowland, the cloudiness is somewhat lower, which should be associated with the western descending air masses crossing the Urals.
On the Murmansk coast and the Kola Peninsula, cloud cover drops to 70%. up to 65% in places. which is similar to the distribution of relative humidity, which is lower here than on the mainland, because the adjacent water bodies are warmer than the mainland and heating from the sea affects the coast. To the west of here, cloudiness increases, reaching 80% in the Baltics. Over the territory of the Karelian-Finnish Republic, the cloudiness is somewhat lower (70%), which is in close connection with the anticyclone that dominates Finland.
Winter isonephs are mainly directed from north to south, since winter is characterized by a decrease in cloudiness from west to east.
In spring, due to the weakening of atmospheric circulation, cloudiness decreases in the west and increases due to an increase in warm air convection in the east.
In summer, cloudiness decreases from north to south (from 70% in the Arctic to 10% in Turan). Over the Baltic coast, the cloudiness is lower (45-50%), which Shenrok explains by the foehn coming here from Sweden. Kaminsky denied such an explanation, since if the masses of air brought by the foehn had reached here, they would have already been moistened as a result of passing over the sea. Studies by Kaminsky, Mikhailovskaya, and others established that summer cloudiness is reduced over flat sea coasts due to weakly developed convective currents; sea winds almost do not experience friction here and do not have time to warm up for the formation of convection.
The most insignificant cloudiness in summer (10% on average in August) is observed in Central Asia. In the North Caucasus, cloudiness is increased due to air masses rising here along the slopes of the mountains, brought by prevailing winds with a northern component.
In summer, in comparison with winter, the distribution of cloudiness is, as it were, rotated by 90 °: in winter, cloudiness decreases from west to east, in summer it decreases from north to south (slightly increasing in the east and decreasing in the west), so that the isonephs now go mainly along the parallels .
Autumn is a transition period. The distribution of cloudiness is close to its annual distribution. In the north, cloudiness is 70°%, in the south (in Central Asia) 20-30%. On the coast of the Baltic Sea, there is no decrease in cloudiness, which was observed in summer.
Closely related to cloudiness is the distribution of clear and cloudy days. The number of clear days on average per year in the USSR ranges from 20 in the White Sea region to 200 in the Turano-Kazakh region, cloudy - from 200 to 20, respectively. ), and Transbaikalia (Chita 140); Transbaikalia is also distinguished by the fact that there are few cloudy days a year (Chita has an average of only 38 cloudy days). The most cloudy weather is characteristic of the White Sea, where the average annual number of cloudy days is about 200, and clear days - no more than 20. In the annual course, the largest number of clear days in the European part of the USSR, Western Siberia and Central Asia occurs in summer. In the Far East and Eastern Siberia, the maximum of clear days occurs in winter.
The greatest probability of cloudy days for the European part of the USSR falls on winter: in January it reaches 80% here, while in the Asian part it is from 30% to 60%, and even 20% in Transbaikalia; in July, the Far East and the Far North of the USSR are the most cloudy (60-70%); Cloudy weather is the least likely in the Turano-Kazakh region (5%).
A. F. Dyubuk gives the following data characterizing the frequency (in%) of clear and cloudy days with various air masses in the European part of the USSR.
The greatest number of cloudy days is in winter, especially during TV and MST. Clear days have a significant frequency (27%) in AV, while they are almost non-existent in mPT and TB.
In summer, the greatest number of cloudy days occurs with AW and CLW, and clear days with MFW and TL.
SUN SHINE
The duration of sunshine per year increases from north to south and from west to east in inverse proportion to cloudiness. So, along the 30th meridian, the number of hours of sunshine per year is: in Pavlovsk (φ=59°4Г) - 1550, in Busany (φ=58°ZG) - 1642, in Novy Korolev (φ=55°09′) -1860, in Korostyshev (φ=50°19′) - 2044, in Odessa (φ=46°30′) - 2200.
An increase in the duration of sunshine from west to east can be seen from the following stations located approximately at the 54th parallel: Suvalki (y, = 22°57′) - 1800, Minsk (y = 27°33′) -1930, Polibino (y = 52°56'1 - 2200, Troitsk (у=61°34′) - 2300, Bodaibo (у=114°13′) - 2088.
However, there are exceptions to the rule. In the east of the European part of the USSR, in Ufa, Molotov and the North Caucasus, there are areas with a short duration of sunshine. These anomalies are due to the intensive formation of clouds here.
Above large industrial centers, where the atmosphere is most turbid, a decrease in the number of hours of sunshine is noticeable. In Leningrad, the average daily duration of sunshine is 3.8 hours, i.e., less than in Khalil (4.1) and Pavlovsk.
In the summer half of the year, the Turan lowland stands out in terms of the number of hours of sunshine: in Bayram-Ali, there is only 7% less sun than in Cairo. In Central Asia, the duration of sunshine in summer reaches 92% of the possible, on the southern coast of Crimea 80%, in Tbilisi 70%, in Gudoire 54%. On the coast of the Baltic Sea, the duration of sunshine is longer than in the depths of the mainland. In the winter half of the year, Transbaikalia (about 1000 hours), Kislovodsk (760 hours), Sukhumi (770 hours) are distinguished by the largest number of hours of sunshine.
The daily duration of sunshine in the warmer half of the year varies in the European part of the USSR from 4.5 hours in the north (Teriberka) to 11.5 hours in the south (Yalta), in the Asian part from 6 hours. in the north (Igarka) until 2 p.m. in the south (Termez). In the cold half-year (October-March), the duration of sunshine ranges from 0 to 5 hours. per day.
The annual course of sunshine is generally opposite to the course of cloud cover. All points in the USSR can be divided into two main groups: 1) stations with one annual maximum, 2) stations with two maxima.
In the north of the USSR, the maximum duration of sunshine occurs in June, i.e., during the period of the polar day.
When moving south, the maximum moves towards autumn, so that in Turan the main maximum is already in August or September.
In Siberia, the main maximum of sunshine occurs in spring, the minimum - in autumn; in the Far Eastern region, the summer minimum and winter maximum of the sunshine duration are sharply expressed, due here to the cloudiness of the monsoon periods. In the south of the European part of the USSR, one maximum occurs in May, the other - in July or August.
Local geographic factors disrupt the regularity of the annual distribution of sunshine duration. For example, in Akatui in the summer in the daytime there is little sun due to the predominance of cumulus and thunderclouds; similarly in Kislovodsk (from May to July especially) the duration of sunshine is less than in a significant part of the European territory
In Siberia, winter is a clear season, and at midday there is more sun than in the rest of the USSR. In the northwestern part of the USSR, there is little sun, especially from November to February, which is associated not only with the short duration of the day, but also with the passage of many cyclones and with the formation of fogs.
The branch of meteorology that studies solar, terrestrial and atmospheric radiation is called actinometry. Its main task is to measure the fluxes of radiant energy. Actinometric data are needed for scientific agriculture, in construction, in the design of buildings and structures, for work and research in the field of solar technology. Solar radiation is widely used for medicinal purposes in balneology.
The sun is the source of energy for almost all natural processes on Earth. The energy coming from the deep layers of the earth, as well as the radiation coming from the stars, is negligible compared to the energy coming from the Sun.
Consider some definitions used in meteorology. The energy emitted by the sun and reaching the earth is called solar radiation. Radiation, (not to be confused with radioactivity - ionizing radiation) entering the atmosphere and then to the earth's surface in the form of a beam of rays, is called straight. The part of solar radiation reflected from the earth's surface and clouds is called reflected radiation. Total radiation is the amount straight and scattered radiation. The composition of the total radiation varies depending on the height of the sun, the transparency of the atmosphere and cloudiness. The daily and annual course of the total radiation is determined mainly by the change in the height of the sun. But the influence of cloudiness and transparency of the air greatly complicates this simple dependence and disrupts the smooth course of the total radiation. The total radiation significantly depends also on the latitude of the place. With a decrease in latitude, its daily sums increase, and the amplitude of its annual variation decreases.
Throughout Primorye, the usual annual course of total radiation is observed with a minimum in December (3.2-6.0 kcal / cm 2 - data before 1951) and a maximum in late spring - early summer (9.2-15.4 kcal / cm 2). At the northern stations of the region, the maximum of total radiation occurs in June, and when moving to southern latitudes, it shifts to May.
If we compare the values of the seasonal values of total radiation for some points of Primorye and the European territory of Russia and Ukraine, located at the same latitude, it turns out that in winter Vladivostok receives more solar radiation than the cities of Krasnodar and Sochi. This is due to the fact that winter in Primorye is characterized by low cloudiness. In summer, in Primorye, the sun appears less often, cloudiness and frequent rains prevail.
Total radiation values (kcal / cm 2)
for some points of Primorsky Krai, Russia and Ukraine
For tourists and vacationers in the south of Primorye, the actual duration of sunshine is interesting. It depends on the length of the day, cloudiness and the closeness of the horizon. The maximum duration of sunshine occurs in March, September and October. The minimum values are observed in June and July. This happens because in spring and autumn the duration of sunshine is quite long compared to the winter months, and the frequency of days with clouds and fogs is much less than in summer.
Radiation balance of the atmosphere and the underlying surface is the algebraic sum of the radiation fluxes absorbed and emitted by the atmosphere. These flows are the main climate-forming factors, the most important components of the heat balance of the atmosphere. It can be positive and negative.
On the territory of Primorsky Krai, the radiation balance for four months (November, December, January, February) turns out to be negative. In the remaining months and for the year, its values are positive. The radiation balance on the territory of the region varies from 22 kcal/cm 2 (Agzu) to 46 kcal/cm 2 (Vladivostok).
It is interesting to compare its values for some points in Primorye and the European territory of Russia. The annual values of the radiation balance for the points of Primorye turn out to be 12 - 18 kcal/cm 2 less than the annual values of the radiation balance for the points of the European part located, respectively, at the same latitudes. This is mainly due to the fact that in Primorye in summer cloudiness significantly reduces the incoming part of the radiation balance.
With the development of the construction of recreation areas and the importance of solar energy for autonomous power supply systems, there is a need for high-quality data on total radiation in the points of Primorsky Krai. Such information can be obtained from the Department of Automation and Regime Hydrometeorology of Primorskhydromet.
The aurora borealis or aurora (Aurora Borealis) is a natural glow (luminescence) of the sky, which is clearly visible, especially at high latitudes, it is caused by the collision of charged particles with atoms in the upper atmosphere (thermosphere).
How are the aurora borealis formed? The charged particles of the magnetosphere, which it captures from the solar wind, are directed by the Earth's magnetic field into the atmosphere. Most auroras occur in regions known as aurora zones, which are typically located 10 to 20 degrees from the magnetic pole, defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, these zones expand to lower latitudes, so that it becomes possible to see the aurora in Moscow.
Classification
Northern lights over the lake
Polar lights as a natural phenomenon are classified into diffuse and point (discrete). Diffuse looks like a featureless glow in the sky that may not be visible to the naked eye, even on a dark night. Spotlights vary in brightness, from barely visible to the naked eye to bright enough to read a newspaper at night. Pinpoint northern lights can only be seen in the night sky because they are not bright enough to be visible during the day. The aurora borealis in northern Russia is known as the aurora borealis.
Northern lights causes
Aurora borealis occurs in the stratosphere near the magnetic pole, it is visible as a greenish glow, sometimes with red impurities. Pinpoint auroras often show magnetic field lines, and can change shape from seconds to hours. When can you see the northern lights? It most often occurs near the equinox.
The Earth's magnetic field and aurora are closely related. The Earth's magnetic field captures particles of the solar wind, many of which then move towards the poles, where they collide with the Earth's atmosphere. Collisions between these ions, atmospheric atoms and molecules and leads to energy emissions in the form of airglow, appearing in the form of large circles around the poles. Aurora is brighter during the intense phase of the solar cycle, when coronal mass ejections multiply the intensity of the solar wind. Auroras on Jupiter, Saturn, Uranus and Neptune can be viewed in this.
South Pole
Are there northern lights at the south pole? Yes, the aurora at the south pole has the same features that are almost identical to the north. Are there northern lights in Antarctica, you ask? Yes, they are visible from the high southern latitudes of Antarctica, South America, New Zealand and Australia.
How the northern lights are formed
It is the result of the release of photons in the upper part of the earth's atmosphere, at an altitude of about 80 km. Molecules of nitrogen and oxygen under the action of charged solar particles pass into an excited state, and upon transition to the ground state, an electron is restored and a quantum of light is emitted. Different molecules and atoms give different colors of glow, for example: oxygen is green or brownish-red, depending on the amount of energy absorbed, nitrogen is blue or red. The blue color of nitrogen arises if the atom restores an ionization electron, red - when it passes to the ground state from an excited state.
The role of oxygen
Oxygen is an unusual element in terms of its return to the ground state: this transition can take ¾ of a second, and emit green light for up to two minutes, after which it turns red. Collisions with other atoms or molecules absorb the excitation energy and prevent the emission of light. In the upper parts of the atmosphere, the percentage of oxygen is low and such collisions are rare enough, which gives time for oxygen to emit a red quantum of light. Collisions become more frequent as we move deeper into the atmosphere, so that closer to the surface, red radiation does not have time to form, and near the surface, even the green glow stops.
Image gallery
Aurora images are much more common today, due to the growing quality and availability of digital cameras, which have a fairly high sensitivity. Below is a gallery of the most impressive shots.
Solar wind and magnetosphere
The Earth is constantly immersed in streams - a rarefied stream of hot plasma (a gas of free electrons and positive ions) emitted by the Sun in all directions, which is formed as a result of the impact of two million degrees of heat from the solar corona.
The solar wind typically reaches the Earth at a speed of about 400 km/s, a density of about 5 ions/cm3, and a magnetic field strength of 2-5 nT (Earth's magnetic field strength is measured in Tesla and near the Earth's surface, it is typically 30,000- 50,000 nT). During , solar plasma flows can be several times faster and the interplanetary magnetic field (IMF) can be much stronger.
The interplanetary magnetic field is formed on the Sun, in the region of sunspots, and the solar wind extends into space along its field lines.
Earth's magnetosphere
The Earth's magnetosphere is formed under the influence of the solar wind and the Earth's magnetic field. It forms an obstacle in the path of the solar wind, distracting it, at an average distance of about 70,000 km (11 Earth radii), and forms a bow shock at a distance of 12,000 km to 15,000 km (1.9 to 2.4 radii). The width of the Earth's magnetosphere, as a rule, is 190,000 km (30 radii), and on the night side a long tail of the magnetosphere, from elongated field lines, extends over huge distances (> 200 Earth radii).
The plasma flux in the magnetosphere increases with increasing density and turbulence in the solar wind stream.
In addition to the perpendicular collision with the Earth's magnetic field, some streams of magnetospheric plasma move up and down along the Earth's magnetic field lines and lose energy in the auroral zones of the atmosphere, which is what causes the aurora borealis. Magnetospheric electrons are accelerated and colliding with atmospheric gases cause atmospheric glow.
Maps of North America and Eurasia with aurora border at different levels of geomagnetic activity; Kp = 3 corresponds to the low level of geomagnetic activity, while Kp = 9 is the highest level.
Auroras in Russia are sometimes observed in temperate latitudes, when a magnetic storm temporarily increases the auroral oval. With the index of geomagnetic activity Кр=6-9 it is possible to see at the latitude of Moscow.
Northern Lights: Forecast
Northern lights in real time (online), update every 30 seconds
Magnetic storms and the northern lights are most common during the peak of the eleven year solar cycle and for three years after that peak. In the auroral zone, the probability of a glow formation depends mainly on the slope of the interplanetary magnetic field.
The axis of rotation of the Sun is tilted 8 degrees with respect to the plane of the Earth's orbit. The solar wind blows out plasma streams faster from the solar poles than from the equator, thus the average velocity of particles near the Earth's magnetosphere decreases every six months. The speed of the solar wind is the highest (about 50 km/s on average) around September 5 and March 5, when the Earth is located at the highest angle to the plane of rotation of the Sun.
Why the Northern Lights Happen
"Wandering Light"
Due to collisions between the molecules and atoms of the Earth's atmosphere and charged particles captured by the magnetosphere from solar radiation. Differences in color are due to the type of gas that is encountered. The most common glow color is a pale yellowish green, which is formed by oxygen molecules located at an altitude of 80 km above the earth. Rare auroras of red color are formed by oxygen atoms at an altitude of about 300 km. Nitrogen is responsible for the blue or purple-red color.
Influence of solar activity
A connection between the northern lights and solar activity was suspected around 1880. Thanks to research since the 1950s, we now know that electrons and protons from the solar wind are captured by the Earth's magnetosphere and collide with gases in the atmosphere.
The temperature above the surface of the Sun (we are talking about the corona, the surface of the Sun itself has a temperature of about 6000 degrees) is millions of degrees Celsius. At this temperature, collisions between ions are quite intense. Free electrons and protons escape from the solar atmosphere as a result of the rotation of the Sun and fly away through gaps in the magnetic field. In near-Earth space, charged particles are largely deflected by the Earth's magnetic field. The Earth's magnetic field is weakest at the poles, and therefore charged particles enter the Earth's atmosphere and collide with gas particles at the poles. These collisions emit light that we perceive as the aurora.
Where is the best place to see the Northern Lights
They can be seen in the northern or southern hemisphere, as an irregularly shaped oval centered over the magnetic pole. Scientists have learned that in most cases, auroras at different poles are mirror images of each other that occur at the same time, with a similar shape and color.
Since the phenomena occur near the magnetic poles, it is convenient to observe the northern lights from the Arctic Circle. They can also be seen on the southern tip of Greenland and Iceland, the northern coast of Norway, and north of Siberia. The auroras are concentrated in a ring around Antarctica and the southern Indian Ocean.
