All about the Atmosphere Part-2

Ionosphere / Thermosphere 

•Extends up to 400 km, contains electrically charged particles (ions) with max. conc. at 250 Km 

•starts rising with increase in height because of ionization by solar radiations 

•Zone of Earths Satellites 

•Auroras →Are formed when Earth’s magnetic field traps solar winds in atmosphere, resulting in collision b/w solar wind & atmospheric charged molecules (ions)  

•Aurora Borealis → Northern light in northern hemisphere (Arctic circle)

•Aurora Australis → Southern light in southern hemisphere (Antarctic Circle)  

•All radio waves are reflected in this layer (Radio transmission)  

•D layer → Reflects signal of low frequency & absorbs of medium & high frequency 

•E layer (Kennedy Heaveside layer) →Reflects medium & high frequency radio waves to earth 

•F layer (Appleton layer) →Useful for long distance radio transmissions → reflects medium & high frequency radio waves to earth 

•G layer → Highest layer.

   

Depletion of Ozone Layer

•Major cause → CFCs (mainly from Refrigerator, AC, Spray Cans, Plastic Packaging, Cleaning Fluids, Insulation materials)

•UV breaks CFCs & release Chlorine atom which reacts with Ozone & convert it into simple oxygen molecule, which is unstable to absorb UV rays 

•Space probes are also responsible for depletion of Ozone layer, as every time a rocket is fired into space, 70 – 150 tons of Chlorine is injected into atmosphere 

•Another cause for ozone layer depletion is oxides of Nitrogen, esp. Nitric oxide, released from supersonic aircrafts, automotive exhaust, in form of nitrates in fertilizers etc.

•Already a major Ozone hole is formed over Antarctica with risk countries New Zealand, Australia, South Africa, Chile, and Argentina etc. 

Auroras 

•Solar flares from Sun (leaving black spots on sun) entering Ionosphere forms Auroras in N & S poles. 

•The auroras appear as sheets of illuminated curtains with streaks or as bright arcs in the sky. 

•These lines or arcs are in the form and directions of the magnetic lines of force of the earth; indicating the involvement of moving charge particles under the influence of concentrated magnetic field of the earth. 

•When they reach the earth, they get concentrated near the poles because of the strong axial magnetic fields there. 

•In other regions of the earth, the magnetic field is weaker and so the aurora does not form although the emission of the solar wind particles takes place uniformly. 

•There is an 11-year solar cycle (on average) that controls the tempo of the aurora. The most recent peak in the cycle occurred in 2000-2001. The next peak is predicted in 2013 – 2014.

Solar Tsunami 

When solar flares are at peak 

•Can disrupts ions in Ionosphere affecting radio waves, GPS 

•Can burn the satellites 

•Can causes skin cancer in human being 

•Increase the frequency of El Nino – Warming of the Oceans

•Can burn transformers