Active And The Northern Lights example essay topic

The Northern lights are poetry, they are nature's light show, and they are quantum leaps in the oxygen atom. They are elementary particle physics, superstition, mythology and fairy tales. The northern lights have filled people with wonder and inspired artists; they have frightened people to think that the end is at hand. More exact explanations of the phenomenon could not be given until modern particle physics were developed, and knowledge about details in the earth's magneto sphere has been based on measurements from satellites. When the northern lights are seen over Tromso, it happens in a set pattern, although this pattern varies considerably.

The outburst starts with glow over the horizon in northwest. The glow dies out and comes back, and then an arch is lit. It drifts up over in the sky. And new arches are lit and follow the first one. Small waves and curls move along the arches. Then within a few minutes a dramatic change is seen in the sky.

A hailstorm of particles hit the upper atmosphere in what is called an aurora sub-storm. Rays of light shoot down from space, forming draperies, which spread, allover the sky. And they really remind us of draperies or curtains, which are flickering in the wind. And you can see a violet and a red trimming at the lower and upper ends. Or the colors are mixed all together, woven into each other. The curtains are disappearing and forming all over again by new rays of light shooting down from space.

Above our head we cans see rays going out in all directions forming what is called an aurora corona. After 10 to 20 minutes the storm is over and the activity decreases. The bands are spread out, disintegrating in a diffuse light all over the sky. We can not see individual pockets of light, but the total effect is bright enough to enable us to make out details of the countryside around us. If we look very carefully, we can see the remains of the northern lights display as faint, pulsating flames. Clouds of light which is turned on and off regularly every 5 - 10 seconds as though by an electric light-switch.

The natures own gigantic light show is over. What causes the northern lights? To answer this, we start with the sun whose energy production is far from even and fluctuates on an 11-year cycle. Maximum production coincides with high sunspot activity when processes on the sun's surface throw particles far out in space.

These particles a recalled the solar wind and cause the northern lights. The sun's surface temperature is approximately 6,000^0 C, much cooler than the interior, which is several million degrees. In the sun's atmosphere or corona, the temperature rises again to several million degrees. At such temperatures, collisions between gas particles can be so violent that atoms disintegrate into electrons and nuclei. What was once hydrogen becomes a gas of free electrons and protons called plasma.

This plasma escapes from the sun's corona through a hole in the sun's magnetic field. As they escape, they are thrown out by the rotation of the sun in an ever-widening spiral -the so-called garden-hose effect. The name originates from the pattern of water droplets formed if we swing a garden hose around and around above out heads. After 2-5 days' travel trough space, the plasma reaches the earth's magnetic field compressing it on the daylight side of the earth, and stretches it into a 'tail' on the night side. A few of the particles penetrate down to the earth along the lines of magnetic field in the polar areas. Most, however, are forced around the earth by the magnetic field and enter the " tail' which stretches out into a long cylinder.

Its diameter is equivalent to 30-60 times the earth's radius, an its length up to 1000 times the same radius. It is, in effect, as if the earth's magnetic field creates a tunnel in the plasma current from the solar wind. Inside one end is the earth, and around its surface the earth's magnetism and the solar wind interact. The magnetic tail is divided into two by a sheet of plasma.

The magnetic field lines from the earth's north and South Pole stretch out in the irrespective halves such that the fields are in opposition. The electrons and protons in each half of the plasma rotate in opposite direction forming a huge 'dynamo' with the positive pole on the side of the plasma sheet facing dawn and the negative pole facing evening. The current of charged particles drives the 'dynamo' between the two poles. When the northern lights break out the following happens. The solar wind strengthens and the magnetic tail becomes unstable. Charged particles dive inwards towards the center of the tail and cause it to increase in length and to taper.

The particles draw the magnetic field lines toward the center where they meet causing a magnetic 'short-circuit' approximately 15 times the earth's radius above the earth on the night side. This occurs especially at the 'dynamo's' two poles where a large amount of energy becomes stored. The magnetic field lines from both sides of the plasma layer now act as conductors in the 'dynamo's' outer circuit The circuit closes when the particles reach the ionosphere, the outer layer of the earth's atmosphere. Here the thin gases are composed of ionized particles and consequently act as electrical conductors. It is here that the " dynamo's' energy is converted to light Most of the northern lights we see originate in the electrons accelerate into the ionosphere. The mechanism by which their kinetic energy is converted to visible light is called the quantum leap.

To explain this mechanism, let us first imagine a hydrogen atom consisting of a single positive proton nucleus around which spins single electrons at a set distance. Normally the electron is in an orbit as close to the proton as possible. In such a state the hydrogen atom a minimum of energy. There are however other possible orbits further away from the nucleus in which the electron can spin. When a free electron collides with the hydrogen electron at high speed, it releases energy. This results in the spinning electron moving into another, higher energy orbit further out from the nucleus.

Itno w contains more potential energy, but is unstable and unable to retain this energy. It returns to its original orbit, releasing the extra energy asa photon of light. Billions of such quantum leaps occurring simultaneously create the northern lights. Only a bare minimum of the aurora is a result of quantum leaps in the hydrogen atom.

The green color, which dominates the northern lights over North Norway, is a result of such leaps in oxygen while red is usually formed in nitrogen. Lars Vega rd was the first scientist to map the colors of the aurora, and his work contributed to the building of the Aurora Observatory in. He used a spectrograph to record the wavelengths, and hence colors of the lights and determined the main green color to be 558 x 10 E-9 m. The particles which stream down from the magnetic tail reach the earth in a belt called the northern lights oval. This belt is wider on the night side of the earth than on the day side and is centered around the magnetic pole while the earth revolves around the geographic poles.

This means that the belt covers Tromso from early evening until early the next morning. The width of the belt on the night side is up to 600 km. A common misconception is that the frequency of the northern lights increases with latitude. This is not so. In fact, when is directly under the belt, the chances of seeing the aurora from Svalbard are less.

The magnetic poles are not stationary such that when the saga was written, the northern lights passed to the north of Norway. That is why they were only seen on Greenland. The northern lights outburst, the way it is described in the beginning of this article, has to do with both how moves in and out under the northern lights oval, and with gusts in the solar wind. In the days of old, the weather forecast was sometimes based on the northern lights. They were however, often contradictory.

In Labrador, colored fine weather, whereas on Greenland they were a sign of southerly winds and storms. Even at the turn of last century, one could read in the Encyclopedia Brittania that the northern lights and thundery weather were the result of the same phenomenon, but with different forms of electrical discharge. In North Norway, the northern lights were often associated with cold weather. Between 1645 and 1715, there was little sunspot activity and therefore little northern lights activity. This period is called the Maunder minimum, after the leader of the Greenwich Observatory in England who was the first to document this low activity. Petter Dass, a famous Norwegian priest an author of the same period, has described much of the North Norwegian way of life, but never mentions the northern lights.

The northern lights oval was then in such a position that the northern lights should have been visible, but the sun was less active and the northern lights failed to appear. During such periods, the climate on earth has generally been colder and the Maunder minimum coincides with what is now known with as the Scandinavian '. Since then, sunspot activity has increased and reached a maximum in 1991. This was the largest maximum in 300 years with more solar energy release, greater sunspot activity and more northern lights. How much today's global warming is a result of increased solar activity is difficult to say, but we do know that when sunspots and northern lights were lacking, the climate was colder in the north. Overview 1) The activity on the Sun produces particles that are thrown out into space.

This stream of particles, called the solar wind, consists primarily of protons and electrons. 2) The particles in the solar wind are captured by the earth's magnetic field. Gathered in the night side of the earth's magnetosphere and then accelerated along the open magnetic field lines down to the Polar Regions. They hit the earth in a narrow belt called the northern lights oval. 3) Seen from space, the northern lights can hang down like a carpet or like draperies. Upper edge red, lower violet and blue, and green in the middle.

4) The aurora activity occurs both around the North Pole and the South Pole at the same time. Around the South Pole it is called the southern lights. Photographs taken from airplanes verify that the patterns are symmetrical. 5) The first indication of a northern lights display is faint glow low on the horizon.

6) The faint glow dies out, but after a while an arch of light is lit. Itc an stretch all over the sky. 7) Bands of northern lights one above the other, raising towards the zenith indicates that the sub storm is starting. 8) Rays of light shoot down from space tells about higher activity.

9) Draperies are formed with waves at the lower end. 10) Curls and waves wave along the draperies. 11) The draperies look as if they are flickering in the wind. Maximum activities close.

12) The interaction between the moving charged particles and the earth's magnetic field creates a charging magnetic field. The particles stream down along the magnetic field lines. 13) Rays and draperies can die out in one place of the sky, and form at another. 14) During the maximum of a sub storm, the whole sky can be full of light.

15) An all-sky (fish eye) picture showing that the draperies are stretched from east to west, through zenith. 16) When the activity reaches Zenith, by an optical illusion, it seems like the rays stretch out in all directions above our heads. This form of the northern lights is called aurora corona.