The Northern Lights

The northern lights or otherwise known as the aurora borealis, is a multi-coloured brilliant light show that can paint the sky with surreal colour.

The creation of the lights start with the sun and the activity it produces. The sun is constantly throwing particles out into space. These particles, often referred to as solar wind, is thrown toward the earth. This wind produced by the sun is a super hot stream of plasma made up of electrons and protons. As the violent wind approaches the earth, much of it is shielded off by the protection cover of the earth's magnetic field. As it hits the earth, the magnetic field guides the plasma towards the northern and southern poles where the particles can enter. As the solar particles enter the earth's atmosphere, they slam into the gas particles in the air. As they collide with each other, they create a glowing effect of different colours. As these lights are created by the solar wind thrown from the sun, they create oval rings around the northern magnetic pole.

In addition to the lights being various colours, they also appear to flow, form different shapes and dance in the sky. This is because the collisions between the atoms and the charged particles are constantly shifting along the magnetic currents of the earth's atmosphere and the reactions of these collisions follow the current.

Today scientists can predict the northern lights which can be shown in a similar way to a weather forecast. Winter is usually the best time to view them because there a re long periods of clear nights. One of the best places to view them is Denali National Park in Alaska.

The Northern Lights, Alaska

Lightning without clouds

Although we associate most, if not all of the lightning storms we see with the cumulonimbus cloud, it is possible to have lightning striking the ground with no cloud what so ever. Most recently, the eruption of the volcano Eyjafjallajokull in Iceland in April 2010 produced a visually stunning natural phenomenon. But how did it happen?

                                Eyjafjallajokull eruption

Volcanic activity can trigger lightning as the enormous quantities of material and gases exploding out into the atmosphere creates a dense plume of highly charged particles. When these charged particles come in contact with neutrally charged particles in the ash, electrons can flow and the ash becomes charged relative to the other particles - think of rubbing a balloon quickly against your head. The same type of charge is building up but on a massive scale. This causes flashes in an attempt to neutralise particles again.

The lightning can be in many forms such as bolt lightning, sheet lightning and St Elmo's fireball (ball lightning).

Are human factors the main causes in many natural disasters?

Hey everyone, I'm very excited about starting my first blog! Hope you like it, feedback is very welcome!

A few weeks ago I was set an essay similar to the title of this post, and through my research for the essay, I came to the conclusion that actually, many reasons behind drastic consequences of earth hazards are caused by human factors, despite it being a NATURAL disaster.

For example, in Venezuela, 1999, a mass movement caused the death of over 50,000 people. Yes, the reasons why the  disaster occurred were natural, 914 mm of rain fell over 2 weeks prior to the disaster caused the flash floods and mudslides. However, thousands of people were exposed unnecessarily to the risk of the disaster as homes were built on alluvial fans on the coast - which had formed due to previous floods and mudslides depositing sediment. Despite knowledge of other debris flows, houses were still built in that area, causing thousands of people and  buildings to be right in the line of fire. If this had not occurred, then many lives would have been saved and the natural hazard would not have caused such disastrous consequences.

                                          Venezuela debris flow, 1999
Another example is La Conchita, California, where there are constant mudflows, causing damages to buildings and some deaths, yet the locals refuse to move away from the hazard.

Of course, there are many natural hazards where the main consequences are due to physical factors. The Tsunami in the Indian Ocean in 2004 main factor was the scale of the disaster and that most of the areas that were affected did not think they would need protection from Tsunamis.

Yet, in many places around the world, people will live knowingly in the risk of earth hazards for simple reasons such as land near a volcano has fertile land, or that floodplains are flat and therefore easy to build on.