Atmospheric Science What causes sudden warming of the stratosphere

The layers of the atmosphere

Similar to the floors of a multi-storey house, the atmosphere is divided into several layers. These layers have different properties - let's start on the "ground floor":

Dark storm clouds or blue skies, gentle breezes or strong winds: almost all weather events take place up to a height of 15 kilometers. This lower layer of the atmosphere is therefore also called the weather layer. Scientists say Troposphere to. About 90 percent of all air and almost all of the water vapor in the earth's atmosphere are contained in this layer. The higher the position in the troposphere, the colder it gets: At its upper limit, icy temperatures of up to minus 80 degrees Celsius prevail.

In the layer above, the stratosphere, the temperature suddenly rises again. At an altitude of around 50 kilometers, the thermometer even reaches a value of around 0 degrees Celsius. The reason for this warming is the ozone layer, which lies within the stratosphere. This works like a heater: it absorbs the sun's UV radiation and converts it into heat.

Above the stratosphere lies at an altitude of 50 to 80 kilometers Mesosphere. Because this layer does not contain ozone, it becomes bitterly cold again, down to minus 100 degrees Celsius. This makes the mesosphere the coldest layer in the atmosphere. Here dust particles and smaller rocks from space are stopped, which would otherwise fall to earth as meteorites. We can sometimes see these celestial bodies as shooting stars in the sky at night.

The air is getting thinner and thinner above the mesosphere. The gravity weakens with increasing altitude and can therefore hold the gas particles less and less. So that forms Thermosphere a smooth transition into space over hundreds of kilometers. The thermosphere takes its name from the high temperatures that prevail here: They rise up to 1700 degrees. In our opinion, however, it is not hot, because too few gases are buzzing around for the feeling of heat.

15.10.2012

The Austrian Felix Baumgartner fell from a balloon capsule from a height of 39 kilometers. In his death-defying jump, he broke the sound barrier and reached a top speed of 1,342 kilometers per hour. After four minutes and 19 seconds of free fall, he was back on solid ground.

“It was much more difficult than we assumed,” Baumgartner said later. Yesterday, over the US state of New Mexico, he let himself be carried into the stratosphere by a balloon capsule. His jump goes according to plan, but shortly afterwards the 43-year-old Austrian gets into a tailspin. Again and again he overturns. The images are broadcast around the globe, and the whole world holds its breath at the sight. "It was brutal," remembers Baumgartner of the near-disaster: "For a few seconds I thought I was going to lose consciousness." Finally, he succeeds in stopping the deadly tumult with his arms.

When he finally lands safely on earth with his parachute, he kneels on the desert sand. He stretches his hands up to the sky: He actually survived the maddening leap. But something else worries him: “I hope we flew supersonic,” he calls out. The measurements confirm: During his jump he broke the sound barrier and reached a top speed of 1,342 kilometers per hour.

This makes him the first person to move faster than sound without an airplane or spaceship. In addition, he now holds the record for the highest manned balloon flight. And never before had a person jumped with a parachute from such a ludicrous height. "Congratulations from us to Felix Baumgartner, a very, very courageous skydiver!" Then congratulated the European Space Agency ESA on Twitter.

Perfect preparation

Felix Baumgartner had been preparing for his life-threatening leap for five long years. Physically he is in top shape. But that's not enough for such a risk: A fire-resistant pressure suit was his life insurance. The heated suit ensured the body temperature during the jump. A hole in it would have been fatal, because temperatures of up to minus 70 degrees Celsius and extremely low air pressure prevail at high altitudes. Oxygen is scarce, so the Austrian was supplied with breathing air through the helmet. During the fall, he was able to maintain contact with his team on the ground through the helmet. He could also have opened an umbrella that stabilized the flight using the emergency buttons on the suit. He didn't use it: that would have endangered his record.

29.5.1931

The Swiss physicist Auguste Piccard and his assistant Paul Kipfer set off on a risky high-altitude flight on the night of May 27th: In a self-constructed gas balloon they reached an altitude of over 15 kilometers after a short time. 17 hours later, after a dramatic journey, the balloon and its crew landed unscathed on a glacier in Austria.

Provisions for two days and oxygen for around 20 hours: Equipped in this way, the aviation pioneers Piccard and Kipfer shoot into the sky at 3.56 a.m. The starting point for their “Ascension Command”, an Augsburg meadow, has been carefully chosen: Piccard doesn't want to land in the water and Augsburg is about the same distance from all seas. There are also steady winds over the city.

The self-made aluminum ball, in which Piccard and Kipfer are wedged, has a diameter of only 2.10 meters. It is equipped with all kinds of measuring devices. Because the two researchers want to explore the cosmic and radioactive radiation in the stratosphere. They have already made a failed take-off attempt, but this time it seems to work: just under half an hour after take-off, they fly over 15 kilometers high. At around 8 a.m., they break the height record: 15,785 meters above the ground, they are the first people to be able to see the curvature of the earth with their own eyes. But up there it gets unbearably hot: the temperature in the aluminum capsule measures almost 41 degrees Celsius. They forgot their water supplies. Tormented by thirst, they lick the condensation from the wall of the sphere.

The aviation pioneers want to land around noon, but the gas valve cannot be opened: a line has become tangled. The wind drives the balloon with it for hours across the Alps. The vehicle is finally sinking. In the evening, at exactly 9 p.m., they finally have ground under their feet again: On a glacier near Obergurgl in the Ötztal, they land hard on a snowfield. A rescue team can only rescue the balloonists in the morning. You are the heroes of this day!

Between hope and fear

In his logbook, Auguste Piccard describes the adventurous balloon ride and the failed attempts to land:

10:10 a.m.: You can't pull the valve rope. We are prisoners of the air. Sentenced to wait until 2 or 3 or 4 a.m. Then we come down.

10:25 a.m .: 39 degrees; Upper body completely undressed. Heat so bearable.

2:08 p.m.: I can't understand why the balloon doesn't want to sink.

As the Alps approach: the sight is overwhelming in and of itself. I have never seen such an abundance of mountains. The clouds that move around the mountains add to the splendor. Everyone has seen them from below. Now we see them from above.

5:50 p.m.: We only have oxygen in the pressure bottle for four hours.

6.48 p.m.: Why, why don't we fall?

7:34 p.m.: I can't understand why we're not sinking yet.

8:29 p.m.: We will not suffocate, but high mountains!

9 p.m .: landing

11.5.1978

No sensible person would have thought that possible: Reinhold Messner and Peter Habeler climbed the highest mountain on earth without an oxygen device. The two extreme mountaineers arrived at the base camp yesterday, completely exhausted but happy.

Your climb to the summit on Everest begins on May 8, in the morning at half past five, after an icy night in a tent. They have been on their way up from base camp since May 6th. They are not frightened by the warnings of many doctors: They want to climb the roof of the world without artificial oxygen. A failed attempt is already behind them. Another attempt now follows from a height of almost 8,000 meters. The ascent in the thin mountain air is an ordeal, every step is torture. But both of them are in top form and they have experience.

At noon they reach an altitude of 8,800 meters. The legs are heavy as lead, the tiredness can hardly be described. But they overcome their pain and trudge on, as if in a trance. Finally they achieve the seemingly impossible: You are standing on the summit of Everest. World record! From exhaustion, they let themselves fall into the snow. After a long break, Messner takes his camera out of his backpack and films. Back in the tent, they radio the base camp: They made it!

During the night Messner is tormented by terrible pain in his eyes: he is snow-blind. Habeler's ankle is injured. Nevertheless, the two manage to descend to base camp on May 10th. Only now do they understand their success, a feeling of triumph fills them. The sensation is perfect: Peter Habeler and Reinhold Messner have proven that Mount Everest can also be climbed without an oxygen device.

In the death zone

Doctors had warned Reinhold Messner and Peter Habeler: Moving around 8,000 meters above sea level without artificial oxygen is extremely dangerous to health. Brain cells could die and suspend controlled thinking, including the threat of unconsciousness. "You will come back as idiots," it was said briefly and drastically.

In fact, altitude sickness is not to be trifled with. From around 2,000 meters, the thinning air can make itself felt through shortness of breath, dizziness, headache or vomiting. The lungs take in less and less oxygen with increasing altitude, and the body is undersupplied. Above 7,000 meters - in the death zone - most people will pass out if they do not get extra oxygen. In the worst case, the extreme altitude leads to death. This fact has already cost many climbers their lives. The fact that Habeler and Messner climbed the summit without breathing apparatus actually borders on a miracle. It can only be explained with meticulous planning, incredible physical fitness and an iron will.

A shell made of gas

Seen from space, it appears like a fine bluish veil that surrounds the earth: the atmosphere. It is the envelope of air that surrounds our planet. Compared to the diameter of the earth, this shell is quite thin: if the earth were the size of an apple, the atmosphere would be about the thickness of its shell.

Without the atmosphere there would be no life on this planet, because plants, animals and humans need air to breathe. It protects us from the cold and from harmful radiation from space. It also lets meteorites burn up before they can hit the surface of the earth. This atmosphere is vital to us - but what is it actually made of?

The atmosphere is a mix of different gases. A large part of this gas mixture is nitrogen: At 78 percent, that's almost four fifths of the entire atmosphere. Only 21 percent consists of oxygen, which we need to breathe. The remaining one percent is made up of various trace gases - gases that only occur in traces in the atmosphere. These trace gases include methane, nitrogen oxides and, above all, carbon dioxide, or CO for short2 called. Although the CO2-Proportion is quite low, this trace gas has a tremendous impact on our earth's climate. This can be seen in the greenhouse effect, which is heating up our planet.

The fact that the earth has an atmosphere at all is due to gravity. It holds the gas molecules on earth and prevents them from simply flying out into space. In fact, the air becomes thinner and thinner with increasing altitude and thus decreasing gravity. Even at 2000 meters above sea level, this can become uncomfortable for people: He suffers from altitude sickness with shortness of breath, headaches and nausea. Extreme mountaineers who want to climb high peaks like the 8000m high in the Himalayas therefore usually take artificial oxygen with them on their tour.

What clouds reveal about the weather

White clouds float in the blue sky like thick cotton balls. Others, on the other hand, tower dark and terrifying. Clouds can look completely different and change constantly. Depending on how and where they appear, they announce different weather. Those who are familiar with the area can tell from the shape of the clouds whether it will soon rain or snow. The height of the clouds also reveals a lot about the upcoming weather.

They are pulling high up, more than six kilometers above the surface of the earth high clouds. These include the delicate feather clouds that contain many ice crystals. If many of them can be seen, they announce bad weather. Small fleecy clouds and veil clouds, which also consist of ice crystals, float just as high in the sky.

They can be found between two and six kilometers in height medium high clouds, for example the coarse fleecy clouds and the layer clouds. When coarse fleecy clouds stretch over large areas, the weather turns bad. Gray layer clouds also indicate that it will soon rain or snow.

In the lowest "cloud level", under two kilometers above sea level, they move deep clouds. They include the bright heap clouds formed by water droplets. This type of cloud is the most common in the world. Because they bring nice weather, especially in summer, they are often called "nice weather clouds". On the other hand, it can rain or snow from deep gray layer clouds. And the darker the cloud looks, the more rain or snow it carries with it.

Clouds that swell several kilometers high over all three “floors” can carry all types of precipitation with them: Far below the water is not yet frozen, there is rain. However, if the drops are whirled up into higher and colder layers of clouds, ice crystals form. Rain, snow or even hail fall from the towering thunderclouds.

Ozone layer

It happens far above our heads, about 15 to 35 kilometers high in the stratosphere: Here the energy of sunlight splits the oxygen into its two oxygen atoms. The individual oxygen atoms react with each other and can also come together in a pack of three. If that happens, ozone molecules are created.

Because the ozone is concentrated in the stratosphere, a layer forms here: the ozone layer. This blocks a large part of the sun's rays and prevents too much ultraviolet radiation from reaching the earth. This is vital because the high-energy ultraviolet rays of the sun can destroy the cells of animals and plants and damage human skin. If the ozone layer in the stratosphere is intact, it acts like a huge protective screen against aggressive UV radiation.

Especially on hot summer days and when there is heavy traffic with a lot of exhaust gases, ozone can also be formed close to the earth's surface. Down here, however, the gas is not useful; it is harmful: it can cause headaches, tiredness, and stinging eyes, and it can attack the airways. If the ozone content on the ground exceeds a certain value, ozone warnings have been issued on the radio, television and the Internet for several years. Then physical exertion in the open air should be avoided.

What are asteroids, meteorites and comets?

On some nights you can observe a special moment in the sky: it looks like a star is falling from the sky. Superstitious people even think that whoever sees such a shooting star could wish for something. But what is really behind it and where do the shooting stars come from?

In our solar system there are not only the sun, planets and moons. Many small pieces of rock and metal have also been discovered. They are much smaller and not as nicely round as planets, hence they are called minor planets or Asteroids. Like their big siblings, they circle the sun in regular orbits. Most asteroids can be found in the "asteroid belt" between the orbits of Mars and Jupiter.

Every now and then two of these asteroids collide. A crash like this creates a lot of debris and splinters. These fly away from the previous orbit, across the solar system. Some of them get close to the earth, are attracted to it and fall to the earth. These falling chunks are also called meteorite.

On earth they would literally fall like a stone from the sky - if it weren't for the atmosphere. Because the meteorites are so fast that the air cannot move to the side quickly enough. The air in front of the falling rock is compressed and therefore extremely hot. The air begins to glow and the meteorite begins to evaporate.We can then see that as a glowing streak that moves across the sky - a shooting star.

Most meteorites are so small that they burn up completely as they travel through the air. The trail then simply ends in the sky. Larger debris also lose mass on the way, but does not completely evaporate. They reach the ground and strike there.

What these meteorites do to the earth depends on how big they are. Small meteorites a few centimeters in diameter, for example, just leave a dent in a car roof.

The largest known meteorite hit about 65 million years ago. It was several kilometers in diameter and tore a crater 180 kilometers in diameter. The impact threw so much dust into the air that the sun was eclipsed for hundreds of years. As a result, plants and animals all over the world died out - this was the end of the dinosaurs.

Fortunately, such large meteorites are very rare so we don't have to worry. In addition, unlike the dinosaurs, we can observe the sky with telescopes and discover such large asteroids long before the impact.

While a shooting star burns up in a few seconds, another phenomenon remains visible longer: Comets with its tail there are days or weeks in the sky. In the past, people also ascribed many properties to them - as divine signs, heralds of calamity or harbingers of happy events. But the truth is a little less spectacular.

Astronomers also call comets "dirty snowballs". They come from the outer solar system, far from the warming power of the sun. It's so cold there that water immediately freezes to ice. This is how lumps of ice and dust form - dirty snowballs.

Even a comet initially travels far away from the sun - until it is deflected by a collision and flies in the direction of the inner solar system. It gets closer to the sun and over time receives more and more light and warmth. This will cause the frozen surface to begin to thaw and even to evaporate. This creates an envelope of water vapor and dust around the comet.

At the same time, the comet gets to feel the “solar wind” - tiny particles that fly out of the sun at high speed. They hit the comet's vapor envelope. This will blow away the comet's vapor envelope, creating an elongated cloud that points away from the sun. When this cloud is then hit by sunlight, it appears as a glowing streak - the comet's tail.

The comet makes an arc around the sun and then moves away again. When it is far enough away from the sun, thawing and evaporation will also stop. The tail disappears and the comet moves like a dirty snowball through the vastness of the outer solar system. Depending on the comet's orbit, it will take many decades or even centuries before it comes close to the sun again.

Northern lights

Northern lights shine red, green or blue in the night sky. As their name suggests, they mostly appear in the polar regions: in the northern hemisphere, especially in northern Scandinavia, Scotland and Siberia, in Greenland, Canada and Alaska. The greater the distance from the pole, the rarer the northern lights become. Most often they appear in the winter months when it is dark for a long time. Then the northern lights can be seen on almost every clear night.

The colorful light effects in the sky have long been a mystery to people. Today their secret has been revealed: The sun is responsible for the glow of the northern lights. Because it not only emits light and heat, but also hurls gigantic masses of matter into space. This so-called solar wind consists primarily of electrically charged particles that race through space at a speed of more than 300 kilometers per second. These energy-charged particles reach the earth after just three days.

Fortunately, we are protected from the impact of these particles by the atmosphere and the earth's magnetic field. In this way they cannot reach the surface of the earth and do not endanger us. Nevertheless, the solar wind affects the earth by deforming its magnetic field: on the sunny side it is compressed, on the side facing away from the sun it protrudes further out into space.

Where the solar wind meets the earth's magnetic field - at an altitude of over 100 kilometers - a strong electrical voltage builds up. Part of this voltage is discharged as the electrons flow to earth along the field lines of the magnetic field. The closest they come to our planet is the poles. When they hit the oxygen and nitrogen atoms in the atmosphere, they emit light - similar to the gas in a fluorescent tube. Depending on the energy of the impact, they glow in different colors. We see the result as colorful northern lights.

Every eleven years, the sun is particularly active and hurls more particles into space than usual. Then the solar wind can turn into a solar storm. Sometimes it is so strong that the northern lights can also be seen in areas outside the polar region. Such a solar storm not only ensures the beautiful northern lights but can also disrupt satellite technology, power lines, radio and navigation. In 1989, for example, the power went out in Canada for days.