Rare and unusual natural phenomena. Unusual natural phenomena

Planet Earth is an amazing place filled with a mass of strange and interesting natural phenomena. Some of them are easy to explain from a scientific point of view, some are a real mystery of nature. Below are the most unusual natural phenomena that not only intrigue, but also fascinate.

The natural phenomenon, which has long been called the "Fires of St. Elmo", was a real thunderstorm for sailors. It looked like small, but rather bright balls of yellow-orange color. During bad weather, a storm or a storm, they appeared on the sharp ends of the masts or the spiers of lighthouses. They frightened and delighted at the same time, seemed interesting and alluring.

It was believed that these lights promise a lost ship hope for salvation, bring good luck in distant wanderings and the protection of the gods.

Elmo's fires were small point charges that were concentrated on the edges of sharp objects. They did not burn and were absolutely safe. It is quite difficult to see these lights at the present time, because modern high-tech ships have smoother shapes.

Stones that can crawl

Once in a few years in Death Valley, a national park in California, USA, you can follow a strange natural phenomenon - crawling stones. Remarkable is the fact that the movement of boulders has not yet been able to be recorded on film. Traces left on the surface of the dried-up Lake Racetrack Playa clearly confirm this mysterious natural phenomenon.

There are a lot of versions and conjectures regarding its origin. According to one of the most interesting, boulders fall from the nearby hills, which reach a height of about 250 meters. The clay soil of the lake at times slows down the inertial movement on a flat surface, but it still happens. As a result, boulders leave behind even traces up to 3 cm deep and tens of meters long.

Green ray of the setting sun

The stunningly beautiful spectacle of the emergence of a green ray at sunset should also be attributed to inexplicable natural phenomena. To see it, you must meet only 3 conditions: find an open horizon, a cloudless sky and clean air.

A strange optical effect lasts only a few seconds (rarely minutes), it is a greenish-emerald flash in the sky at the moment the sun disappears below the horizon.

Researcher William Cohn tried to explain the appearance of the green beam as follows. When oxygen atoms pass to the normal state from the metastable state, they are emitted. It is expressed in a light wave, which tints the horizon green. This conjecture has not yet been confirmed scientifically.

Mystical mirages of the desert

Anomalous natural phenomena are not uncommon for endless sandy areas. Often in the desert you can observe the appearance of mirages. Strange and interesting, inexplicable and incomprehensible, they are illusions and images floating in the air.

There are many conjectures and explanations for their occurrence:

• the whim of the gods;
• tribute to the past;
• secrets of science.

According to ancient Egyptian beliefs, mirages are a reminder of the past, the appearance of objects, people, even cities that no longer exist. According to one of the legends of England, Fata Morgana was considered the ruler of mirages, who deceived sailors with ghostly visions.

From a scientific point of view, mirages are the consequences of temperature overheating of the air, the creation of the so-called "air lens". Quite interesting is the fact that the clearest mirages appear not in sandy deserts, but in icy ones. So, in Alaska, the centuries-old cold enhances light inhomogeneities and leads to the emergence of stunningly bright air illusions.

Electric lightning extravaganza Catatumbo

The real attraction of Venezuela is the Catatumbo River, or rather, the place where it flows into Lake Maracaibo. Here you can quite often observe a strange and bewitching phenomenon of nature - a huge concentration of electric charges in the atmosphere. Catatumbo lightning appears up to 150 times a year and continues to sparkle up to 10 hours in a row. This phenomenon is not accompanied by any sound effects.

All this allowed the Venezuelan municipality of Catatumbo to proclaim its territory the Capital of Lightning. This rather interesting phenomenon has been known since the time of ancient navigators: lightning discharges, which were visible for 400 km, served as a kind of beacon for them, were used for navigation.

To date, the phenomenon of the multiplicity of Catatumbo lightning is explained quite simply. Several unique natural factors came together:

• The Andes cut off wind access to the lake;
• evaporated water forms massive clouds;
• electrical discharges occur in the clouds.

As a result of all this, unusually beautiful and high lightning occurs, and a huge amount of ozone is released into the atmosphere.

Cellular clouds - storm harbingers

Another exciting natural phenomenon is cellular, also called biconvex, clouds. They were discovered quite recently, no more than 40 years ago. It belongs to the category of cumulonimbus clouds. Their structure is quite interesting, reminiscent of a kind of convex honeycomb. The elements hanging down are tinted with dark gray. In the case of a low location of the sun above the horizon, they can acquire pinkish, golden, bluish hues.

They are found mainly in the United States, with their appearance they portend the imminent approach of a storm or hurricane. Strange cloudiness is especially recommended to be avoided by airplanes and helicopters, since ball lightning often occurs in cellular clouds, frequent and sharp changes in the wind occur. Biconvex clouds are also unique in that they form on descending rather than ascending air currents.

miraculous aurora borealis

One of the most strange and mysterious wonders of nature is the northern lights. A stunning sight can be seen in clear, calm weather near the Earth's magnetic poles. The duration of the northern lights varies from 1-2 hours to several days and depends on solar activity.

In itself, this phenomenon represents the glow of the upper atmospheric layer of our planet, which is formed as a result of its interaction with the flow of the hydrogen-helium plasma of the Sun. When the particles collide with each other, the molecules and gases of the atmosphere are activated. Their radiation appears before us in the form of a magnificent and interesting phenomenon- northern lights. Its color palette glows purple when nitrogen is activated, scarlet and emerald when oxygen is excited.

The latest discovery of scientists who conducted research on this natural phenomenon was the confirmation of the sound effect aurora borealis. A research team from Aalto University, Helsinki, made an audio recording of the light flashes. Numerous legends about the "voices of the luminous sky" were confirmed.

Incredible Facts

1. Water bloom

When the ocean, air, and temperature conditions permit, ocean phytoplankton reproduce fairly quickly, creating a thick, visible layer on its surface.

This phenomenon, called a water bloom, looks rather unsightly during the day, but in parts of California and other places where there are bioluminescent nightlights, the water bloom is a truly spectacular sight. This species of phytoplankton glows blue when agitated, turning the dark ocean into a giant lava lamp.

You can watch the waves begin to glow on impact as they ripple across the sand, and the earth begins to shine under your feet, and if you dive underwater, you will see an amazing radiance in all its glory.

2 Bioluminescence

Bioluminescence does not only occur in water. In late summer, an uncanny glow can be seen in many of the world's forests, where bioluminescent fungi grow on damp, rotting bark.

Bioluminescence can be observed in different parts of the world, but the greatest diversity occurs in the tropics, where the moisture in the forests promotes the growth of fungi. A new species of glow-in-the-dark mushroom has been discovered in Sao Paulo, Brazil.

If you want to admire this phenomenon, then plan to go to the forest during the wettest period and head away from light sources that can dim the faint glow.

3 Fire rainbow

Another natural phenomenon that occurs in the summer is called a fiery rainbow, and occurs when sunlight hits frozen ice crystals in cirrus clouds at high altitude. Since there is no rain during a fiery rainbow, scientists prefer to call it a more accurate name. circumhorizontal arc.

Since this phenomenon requires the presence of cirrus clouds, and the sun must be very high in the sky, it can often be observed at latitudes closer to the equator. In Los Angeles, conditions allow you to observe a fiery rainbow for six months of the year, and in London for about two months.

4. Pearly clouds

For those of us who are far from the equator, there are many more reasons to look at the sky. Mother-of-pearl clouds are quite rare, but most often they appear when it is still dark outside before dawn or after sunset. Due to their extremely high altitude, they reflect sunlight from below the horizon, glowing brightly for those who watch them from below.

In the lower stratosphere, where mother-of-pearl clouds are located, it is so dry that it often prevents the formation of clouds, but the harsh cold of the polar nights makes it possible to see this most beautiful phenomenon. You can see mother-of-pearl clouds in winter at high latitudes, such as in Iceland, Alaska, northern Canada and very rarely in the UK.

5. Snow rollers

Snow rolls form when a thick layer of snow falls on top of the ice. At certain temperatures and wind speeds, chunks of snow can break loose and begin to curl. As they roll along the ground like winter tumbleweeds, they pick up more snow along the way. The inner layers tend to be more brittle, allowing the wind to easily blow them away, leaving large natural snow donuts.

Since a certain temperature and wind speed are needed to create this effect, snow rolls are rare, but can be seen in North America and the UK.

6. Basalt columns

Natural volcanic formation - basalt columns look like they were made by man. The hexagonal columns form naturally when a thick layer of lava cools rapidly, shrinking and creating cracks in the surface of new rock formations.

Unusual geological formations can be seen in all corners of the world. The most striking examples of basalt columns are Road of the Giants in Ireland and Devils Postpile National Monument in California.

7 Animal Rain

Whereas in the small town of Yoro in Honduras every year fish rain festival, there are still quite a few actual eyewitnesses of this phenomenon. However, in general, such a phenomenon has been reported in different parts of the world for many centuries. Most cases of animals falling from the sky have included fish, frogs, or small aquatic animals, although there have been reports of birds, mice, and even chunks of meat falling.

Although such a phenomenon is extremely rare, most cases are easily explained. The most obvious explanation is tornadoes, during which a whirlwind lifts small animals from the water, carrying them over long distances until they fall on your head. If you want to witness the rain of animals, then you should go to places close to the water during big storms.

8. Wavy clouds

Recently discovered cloud formations, so-called wavy clouds ( Asperatus clouds) are so rare that they were not included in the classification until 2009. Ominous and stormy, these clouds disintegrate rather quickly before causing a storm. As with most wavy clouds, these clouds form when eddies or oncoming air masses ruthlessly churn the lower layers of clouds, resulting in bizarre shapes and formations.

Such clouds are more common on the plains in the US and can be observed in the morning or mid-afternoon during thunderstorms.

9. Green beam

Famous and Elusive green beam is a rare meteorological phenomenon that occurs during sunrise and sunset. During these periods, the sun's light passes through large layers of the atmosphere, creating a prism effect. Of course, this explanation is not as exciting as the maritime legends that surround this phenomenon. But you can consider yourself lucky if you managed to observe this phenomenon.

To see the green beam, try watching the sun rise or set on the horizon on a clear day. An ocean or prairie horizon is best suited for this purpose. The green beam lasts only a fraction of a second, so don't blink.

10. False sun

When the sun is near the horizon and there are ice crystals in the air, you may see a few bright rainbow spots on both sides of the sun. Always to the right and left of the sun along the horizon, these halos faithfully follow the sun across the sky.

While this atmospheric phenomenon can happen anytime, anywhere, the effect is usually quite subtle. When sunlight passes through cirrus clouds at just the right angle, these patches become as bright as the sun. False suns are most visible when the sun is low in the sky in colder regions where there are many ice crystals in the sky.

11. Double rainbow

The same forces that lead to the formation of an ordinary rainbow can also lead to the creation of a double rainbow. Sometimes, sunlight is reflected in the raindrops not once, but twice, resulting in a second rainbow that is behind the brighter first rainbow.

It is best to observe this phenomenon when the sky is still dark and filled with clouds, as the dark background allows you to see the more vague colors of the second rainbow.

12. Striped icebergs

Icebergs, as a rule, are not uniform. Some icebergs in the polar regions are distinguished by their color bands, standing out from the arctic whites and blues. When water on an iceberg melts and refreezes, dirt and other particles can get trapped between the new layers of ice, causing colored streaks to form on their surface.

Icebergs may show several colored bands. Blue streaks appear when water enters between layers of ice and freezes so quickly that air bubbles don't have time to form. When an iceberg breaks and falls into the ocean, algae and other materials present in the water can cause green and yellow streaks to appear.

The only place where you will be able to observe this phenomenon is, of course, Antarctica.

13. Lightning Catatumbo

Enough mysterious phenomenon, Catatumbo lightning in Venezuela is known for its continuous discharges. This incessant lightning bolt can be seen from a distance and has often been noted for its ability to aid sailors in navigation.

Since Catatumbo lightning strikes about 140-160 nights a year, you have a good chance of seeing them. They occur mainly in one place - above the confluence of the Catatumbo River around Lake Maracaibo.

14. Gravitational wave

Waves occur not only in water, but also in the sky. When the air is pushed up by the more stable layer of the atmosphere, it can cause a ripple effect, just like what happens when you throw a rock into a pond.

For a gravitational wave to occur, interference must occur in the atmosphere, such as the updraft of air from a thunderstorm. According to recent research, gravity waves can concentrate and intensify tornadoes, so if you happen to see them, you should first take care of the shelter.

15. Moeraki Boulders

The Moeraki Boulders are spherical stones that were naturally excavated from mudstone, a dense clayey rock on the New Zealand coast.

People discovered these giants through erosion, but they acquired their spherical shape for a different reason. It is believed that boulders formed millions of years ago on the ocean floor, much like pearls formed in oysters - layers of sedimentary rocks and materials crystallized around a central core. Over the course of millions of years, they have grown to the gigantic proportions we can see today.

Moeraki boulders have been found along the south coast of New Zealand, but they can also be seen in various parts of South America.

The 10 most unique natural phenomena that are included in the top of this list are ten wonderful wonders created by nature, biology, physics, chemistry and other fields. You can personally see and experience all these wonders. To do this, you just need to go to a specific area of ​​\u200b\u200bour beautiful planet, which is called Earth.

In our world there is a huge number of miracles created in natural conditions, some of which can cause an ocean of positive emotions and admiration. 10 natural phenomena and events spread all over the world create an unsurpassed atmosphere, immersed in which, a person experiences great pleasure from the world around him.

(10 photos of natural phenomena and phenomena + video)

One of the most spectacular and unique natural phenomena that can be observed near the North and South Poles (around the Arctic and the Antarctic Circle) is the Northern Lights. It arises from charged atoms and particles in the upper atmosphere, which predominantly originate in these areas of the Earth. Simply put, this phenomenon occurs when the solar wind comes into contact with the Earth's magnetic field. Undoubtedly, one of the best places to observe this beautiful phenomenon is Lapland (Northern Finland). In this place you will encounter wild nature, uninhabited areas where clear transparent skies, devoid of city lighting, air pollution and telecommunication signals, create unique conditions for observing this natural phenomenon. The Aurora Borealis is a romantic marvel as it originates at high altitude and is a multicolored (yellow, green, blue, red and purple) river flowing among countless stars.

If you want to plunge into the world of illusions and dreams, feel a sense of inspiration, tubular clouds of an unusual shape will help you with this. The unique shape of these clouds is somewhat like huge pipes with different shades (from white to darker). The color of such clouds depends on their thickness. Tubular clouds can be observed in many places where thunderstorms begin to form. Their indescribable beauty is especially noticeable at sunset, when they are formed into groups of balls with a smooth structure.

The most beautiful creature on Earth is by far the Monarch Butterfly. They can only evoke feelings of love and admiration. These butterflies will show you the bright weaves of black and orange. Most often they are found in Mexico, the USA and Melanesia (northeast Australia). The best place to observe Monarch butterflies is the United States during the time when they migrate from Canada to Mexico and back. Walking through the parks of California, you can witness when the leaves and branches of the trees are painted in black and orange colors, as Monarch butterflies are completely dotted.

Have you ever observed strange formations of snow and ice, which are pillars up to 2 meters high? These amazing pillars are called penitentes. They can be observed in the region of the most elevated places (up to 4,000 meters high) of the central Andes in the territory between Argentina and Chile. You can see these wonderful natural phenomena while hiking in the mountains. Excursions of this kind will help you learn more and explore the peculiar phenomenon of the Andes - penitentes.

In the National Park called "Death Valley" in California, you can observe such a natural phenomenon as moving stones. In this park, among the unusual mountain landscape, you can see one of the most mystical and picturesque dry lakes of Racetrack Playa. The main feature of this lake is the stones moving along its dry bottom. Traces of stones are clearly visible on the surface of the desert. This phenomenon is one of the geological mysteries, which, according to scientists, is created by winds and other natural factors. If you managed to visit this unusual place, surrounded by dramatic mountain peaks, over which shapeless clouds float, you can consider that you are really lucky.

No less striking are the Supercell clouds. These storm clouds can appear almost anywhere where there is a humid climate characterized by frequent thunderstorms. Some of the most famous places to see super clouds are in the central states of the United States, which are part of Tornado Alley. The plains of Nebraska and Dakota will allow you to fully appreciate this natural phenomenon. The natural variation of daylight will enchant you as you watch the Supercells at sunset. Pay attention to a selection of beautiful photographs that reveal the wonderful world of these clouds.

The most beautiful and graceful fiery phenomenon, which is created with the help of vertical whirlwinds, is a fiery tornado. However, do not forget that the amazing beauty of this natural phenomenon is simultaneously fraught with danger and destruction. This natural phenomenon can be observed in a fire or a burning forest, where a tornado is born, the wind speed of which is over 160 kilometers per hour. This is enough a rare event which is both magnificent and tragic. The fiery tornado is an attraction for photographers and extreme enthusiasts.

A natural phenomenon like sandstorms is quite typical for some areas of the Earth. Sandstorms are created by strong winds and storms that prevail in dusty areas with arid climates. During such storms, sand particles are picked up by strong winds, which accelerate their movement in the atmosphere. Some of the most famous places where such natural phenomena can be observed are in northern Africa (Sahara Desert), as well as deserts in Asia. This phenomenon can be called surprising without exaggeration. However, fierce storms are quite dangerous, since small particles of sand penetrate almost everywhere. It is impossible to imagine a more inspiring landscape than watching sandstorms in the area of ​​the Great Pyramids of Egypt.

A natural phenomenon - a rainbow is able to give everyone colorful emotions. Rainbow is one of the most common natural phenomena, which can consist of small arcs with thin multi-colored layers, as well as huge arcs stretching for hundreds of kilometers. The double arched rainbow is majestic and inspiring at the same time. optical illusion. This natural phenomenon occurs due to small tiny particles of water and the rays of the sun and is most often observed after rain, when water evaporates under the bright rays of the sun. Most often, this natural phenomenon can be observed in the area of ​​​​water basins - lakes, rivers and other reservoirs.

Most of us have seen these natural phenomena only in films or on the Discovery Channel. I present a detailed description with photographs of the most incredible natural phenomena. You can read about the phenomena that I talked about earlier by clicking on this one.
1. Water bloom: in more detail we considered neon lakes

When the ocean, air, and temperature conditions permit, ocean phytoplankton reproduce fairly quickly, creating a thick, visible layer on its surface. This phenomenon, called a water bloom, looks rather unsightly during the day, but in parts of California and other places where there are bioluminescent nightlights, the water bloom is a truly spectacular sight. This species of phytoplankton glows blue when agitated, turning the dark ocean into a giant lava lamp. You can watch the waves begin to glow on impact as they ripple across the sand, and the earth begins to shine under your feet, and if you dive underwater, you will see an amazing radiance in all its glory.

2. Bioluminescence

3. Fire rainbow

4. Pearly clouds

5. Snow rollers

6. Basalt columns

7. Rain of animals: we examined it in more detail

8. Wavy clouds

9. Green beam

10. False sun

11. Double rainbow

12. Striped icebergs

13. Lightning Catatumbo

14. Gravitational wave

15. Moeraki Boulders

Volcanic lightning

The cause of ordinary lightning in thunderstorms remains a matter of research, and the nature of volcanic lightning is even less understood. One hypothesis suggests that ejected magma bubbles or volcanic ash carry an electrical charge and that such separated regions are created as they move. However, volcanic lightning can also be caused by charge-producing collisions in volcanic dust.

fiery rainbow

This colorful phenomenon can be seen during the summer season in mid-latitudes such as most of the United States. In fact, it is a large halo of refracted light, and, despite the name, has nothing to do with either fire or a rainbow. It only appears when the sun is at least 58 degrees above the horizon and when there are cirrus clouds in the sky that are filled with lamellar ice crystals. The refraction of light is always parallel to the horizon, and due to the fact that the arcs are very large, only sections become visible, which is why it can look like patches of clouds on fire. Fiery rainbow in the sky over Florida:

Lunar rainbow.

We are almost used to the usual rainbow. A lunar rainbow is much rarer than a rainbow seen in daylight.

A lunar rainbow can only appear in places with high humidity and only when the moon is almost full. Appearing at the opposite end of the sky to the moon, they usually look completely white due to the faint coloration, but a long exposure photo can capture the true colors, as in this photo taken in Yosemite National Park, California:

discoid clouds

Discoid (lenticular, lenticular) clouds is a term for a rather rare natural phenomenon, reminiscent of the notorious “flying saucer”. Such clouds form on the crests of air waves or between two layers of air. A characteristic feature of these clouds is that they do not move, no matter how strong the wind is. The flow of air rushing over the earth's surface flows around obstacles, and thus air waves are formed. They usually hover on the leeward side of mountain ranges, behind ridges and individual peaks at an altitude of two to fifteen kilometers.

Another example of such a cloud:

Monarch butterfly migration

This is one of the most beautiful sights on the planet. Thousands of bright orange moths in a single impulse can overcome an impressive mileage, flying from Canada to Mexico and back. Perhaps one of the most interesting facts about the migration of butterflies is that during the flight three or four generations of insects are replaced. Despite this, the Monarch butterfly colony is able to cross the Atlantic, and few people can boast of such achievements.

false sun or parhelion

A bright round spot in the firmament on one side or on both sides of the solar disk. Most often, this is a luminous ring that forms around a light source, but sometimes the shape of a parhelion can be different, sometimes they take the form of a pillar, a cross, and sometimes they look like a rainbow. Such an amazing phenomenon arises due to the refraction of light in ice crystals, at an altitude of 5-10 km, it depends on the location of the crystals how parhelion will look.

tubular clouds

They are rare, mainly in tropical latitudes and are associated with the formation of tropical cyclones. Cells usually have a size of about one and a half kilometers.

underwater icicles

When the surface of the sea freezes, for example around the north and south poles, the process is such that pockets of particularly cold and salty sea water remain on the underside of the ice. This salty mixture is denser than sea ​​water under it, and tends to slowly sink to the bottom. Now because of the cold cold water below the salt mass freezes around it as it sinks, resulting in a giant icicle below the ice surface. This phenomenon was first discovered in 1960.

green beam

It is considered to be a rare optical phenomenon: lasting from 1-2 seconds to 5 minutes, manifesting itself in the form of a flash of green, less often blue light at the moment the solar disk disappears below the horizon (usually sea). Many peoples of the world have a legend according to which, if someone sees the "Green Ray" at sunset, he will find forever a happy and rich fate, which will bring him nothing but joy in life.

Supercell Thunderstorm

Supercell thunderstorms are relatively rare, and typically occur in the central US in the spring, but pose the greatest threat to human health and life and property. Formed by a huge rotating thundercloud 10-15 km high and about 50 km in diameter and creating extreme weather events: tornadoes, heavy winds, large hail.

pillar of light

Reflection of light by ice crystals with almost perfectly horizontal flat surfaces creates a strong beam. The source of light can be the Sun, the Moon, or even artificial light. Interesting feature is that the column will have the color of this source. In this photo taken in Finland, the orange sunlight at sunset creates an equally gorgeous orange pole:

"Morning Glory"

The natural phenomenon "Morning Gloria" is very rare in nature. Clouds gather into a kind of storm collar, which is located at a height of 1-2 kilometers above the ground. The length of these clouds can reach 1000 kilometers. Similar clouds can be found in Russia, in Europe, in the USA, as well as in other places on our planet. And only in Australia near Cape York "Morning Gloria" is constantly formed in the spring. This atmospheric phenomenon is very actively studied by specialists from all over the world, but today its nature has not been fully elucidated. There are many speculations on this subject. One of them is that these are sleeping tornadoes, another is that they are spiral arms of cyclones, and still others are that they are a squall gate that appears before a thunderstorm. But the problem is that such clouds often appear in clear weather.

Moving rocks in Death Valley

This mysterious natural phenomenon is observed in Death Valley National Park, California. Among this bare space are scattered boulders - seemingly the most ordinary, ranging in size from a soccer ball to half a ton in weight. And these stones tend to change their location, leaving visible traces of their movement.

Firestorm

The fire tornado is probably the most beautiful and graceful phenomenon associated with fire, which is created by the vertical forces of the whirlwind. Except for its amazing beauty and magically bright forms, the fire tornado is also very dangerous and destructive. It occurs in areas where tornadoes originate from fire or burning woods, while wind speeds often exceed 100 miles per hour. Such a phenomenon is very rare, and the sight of it is as magnificent as it is tragic. Fire tornadoes are real attractions for extreme enthusiasts and photographers.

The immiscible waters of the seas

The Strait of Gibraltar, which connects the Mediterranean Sea and the Atlantic Ocean. The waters seem to be separated by a film and have a clear boundary between them. Each of them has its own temperature, its salt composition, flora and fauna. Earlier, in 1967, German scientists revealed the fact of non-mixing of water masses in the Bab el-Mandeb Strait, where the waters of the Gulf of Aden and the Red Sea, the waters of the Red Sea and the Indian Ocean converge.

And perhaps the most beautiful thing is Northern lights, although it is not at all rare in the polar latitudes.