Geomagnetic storm is an atmospheric phenomenon and its effect can be felt on earth too, hearing the word storm leads to think of a massive lightening, wind etc. let’s short our curiosity out about everything there is to know about it.
What is Geomagnetic storm
Also known as solar storm, it is caused by a major disturbance of Earth’s magnetosphere and our Sun is responsible for this. To understand it clearly let’s take a look at Sun’s structure, it can be classified into 4 parts-
- Photosphere
- Chromosphere
- Transition Region
- Corona
The outer atmosphere of Sun known as corona is mainly responsible for the large eruption.
This type of storms are result of major disturbance of Earth’s magnetosphere that arises when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth brought by the coronal mass ejections (CME).
What causes a Solar storm
Solar wind leads to these storms and they end up producing major changes in the currents, plasmas, and fields in Earth’s magnetosphere.
The protons and electrons are the primarily associated materials with these eruptions having energy of order of few thousands electron volts.
And plasma, moves through the space at speeds ranging from 6 miles/sec. (10 km) to approx. 1200 miles/sec. (2000 km) and the ejected material reaches Earth in about 18-22 hours.
The pressure at the outer edge of magnetosphere due to the transmission of incoming plasma leads to geomagnetic field at the ground.
Apart from CME the other contributor to these storm is high-speed solar (HSS) wind, a sustained period of it contribute in creating these geomagnetic storms, as well as a magnetic field directed opposite (southward directed) to Earth’s magnetic field leads to the transfer of energy from the solar wind to Earth’s magnetosphere.
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Impact of Geomagnetic Storm
When the matters from solar wind collides with the planet Earth at speed very high the magnetic field gets deflect towards the poles.
In the polar region the injected plasma interacts with gases and result in displaying an intense light, an auroral displays known as auroras. Whereas these contractions can be observed on earth and known as a polar sub storm. Famously known as ‘Northern Lights/Southern lights’.
In the meantime, the fast-moving charges create an intense magnetic field of their own, which further induces a set of electrical currents on the ground far below.
Stages/Phases of Solar Storm
In simple words, in the beginning of the storm there is a flash of electromagnetic radiation, which hardly takes a few minutes to strike Earth. Following that protons and electrons are accelerated close to the speed of light in jets of plasma, which can last from a few hours to few days.
During extreme periods of solar activity, the magnetic field of Sun break and reconnect. This can eject a slow-moving cloud of charged particles in a final stage of solar storm which we know as CME (coronal mass ejection). For ease we can categorize these events in three phases.
Initial Phase – After few minutes the horizontal component of the geomagnetic field increases abruptly over the entire globe. This increase leads to the initial phase of the storm and continues for 2 to 6 hours.
Main Phase – This portion of the storm is followed by the storm’s main phase, lasting 12 to 48 hours, during which the horizontal component of the field decreases, because of the injection or inflation of the magnetosphere by the incoming plasma.
Final/Recovery Phase – At this stage the newly injected plasma drains slowly over several days into the interplanetary medium or the atmosphere, and the geomagnetic field approaches its pre-storm condition.
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Historical Facts about Geomagnetic Storm
- A Geomagnetic storm named The Carrington Event was absorbed from 28 Aug 1859 – 2 Sep 1859.
- It was named after the British astronomer Richard Christopher Carrington who witnessed it on 1st September 1859.
- While observing, Carrington noted two dots within the dark patches brighten and fade over a number of minutes.
- He didn’t think the two were connected as he said – “One swallow doesn’t make it summer”.
- The brightening he saw was a white light flare, caused by reconfigurations in the Sun’s magnetic fields, releasing huge amounts of plasma and radiation in phases.
Effects we feel on the earth
- The currents and charged particles add energy in the form of heat which causes multiple damages to low-earth orbits.
- This heat can also abrupt the path of radio signals and cause error in the information provided by Global Positing System as well as in the navigation system.
- It also creates a harmful geomagnetic induced currents (GICs) in the pipelines and power grids (can lead to multiple blast and blow transformers).
- Disruption of various satellites leads to disruption of electronic communications (mobile phone signal and satellite TV).
