Ozone hole, a drastic depletion of ozone in the atmosphere layer over the Antartic, was noticed by scientists in the early Eighties. The depletion was found to be periodic and far greater than expected from other calculations of the chloro-fluro-carbon effect. So the question arose:
Was this a natural climate variation or was it a chemical decomposition brought about by mankind? In spite of the pioneering research by many researchers, among them Paul Crutzen, Mario Molina and F. Sherwood Rowland who shared the 1995 Nobel prize for chemistry, as well as Susan Solomon and James Anderson of the U.S. the mystery has not been fully understood.
It has been proved beyond doubt that ozone depletion is caused chiefly by ozone reacting chemically with chlorine and bromine from industrially manufactured gases. But, the rapid depletion of ozone over Antarctica could not be explained by transport processes or by gas phase chemical reactions.
According to an information note from The Nobel Foundation of the Royal Swedish Academy, an alternative mechanism must exist which could accelerate the decomposition of ozone. In fact, scientists have identified this mechanism as chemical reactions on the surface of cloud particles in the stratosphere.
Thus, the Antarctic ozone depletion appears to be connected with the extremely low temperatures, which lead to condensation of water and nitric acid to form ‘polar stratospheric’ (PSCs). The ozone-decomposing chemical reactions are greatly reinforced by the presence of these cloud particles. This understanding itself has lead to an exciting new branch of atmospheric chemistry called ‘heterogeneous’ chemical reactions on particle surfaces.
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What are cosmic rays?
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Cosmic rays are electromagnetic waves of extremely short wavelength. As the word suggests their origin is from outer space or the cosmos. These rays consist of positively charged particles coming from various galaxies outside the solar system and comprise mainly of protons, alpha particles and positive ions of some heavy elements. The sun is a poor source of cosmic rays.
The distant galaxies are the store houses of charged particles. The high electric and magnetic fields present in these galaxies act as natural accelerators of these particles. The high velocities and the charged nature of these particles attribute the wave nature of these particles. Work on the cosmic rays was first stated by Millikan and Anderson during the early part of this century on balloon flights. The intensity of these rays has been found to vary with altitude, latitude and depth under the sea. The primary cosmic rays interact with the molecules of the atmosphere giving rise to secondary particles like electrons positrons (positively charges particles) and mesons. In fact the anti proton was discovered during cosmic ray studies. Luckily, the thick atmosphere around us is a natural blanket protecting us from these rays.
The work of Vikram Sarabhai and Homi Babha on cosmic rays has given us an immense knowledge on the particles that are fundamental constituents of matter and also an insight into the forces that bind them.
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What is solar wind?
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Solar wind is a combination of electrically charged stream of atomic particles – electrons, protons, with small proportions of heavier nuclei and the entrained solar magnetic field emitted from the sun’s atmosphere.
E. N. Parker in 1958 showed that due to the very high temperatures of the corona the pressure exerted results in an outflow of material into the interplanetary space in all directions in a phenomenon he called “solar windâ€. Solar wind is an extremely radially outward at a speed of 500 kilometres per second which is variable in response to the varying solar activity.
The particles normally takes about 4 to 5 days to reach earth. The radial flow of the solar wind and the rotation of the sun, wind the solar magnetic field into a spiral which makes an angle of 45 degrees at the earth’s orbit. The study of the solar wind becomes important as it contributes to the phenomenon such as aurorae and magnetic storms.
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Where does dust come from and why does it reappear so soon after we dust?
Terrestrial dust is mostly tiny fragments abraded from things; some of it may be even smaller things aggregating together to form motes of dust. The larger things that turn to dust can be almost anything in the world, from shoes to ships to sealing wax, not to mention cabbages (fragments of dried vegetable matter) and kings (especially if cremated).
Wind-driven dust composed of fragments of stone and clay is so powerful that over the millennia it has cut fantastically shaped canyons and pillars in the badlands of the American west. Drought created the dust Bowl with its penetrating clouds of dry ploughed soil; the fires of ancient plains Indians probably added to the dust in teepees; soot from unburned automobile fuel plagues city apartments.
Dust knows no borders, and dust from volcanic ash lingers in the upper atmosphere to produce brilliant sunsets thousands of miles away from the eruption.
As for why dusting seems worse than futile, one reason is that a dust cloth may simply stir up dust temporarily while the friction simultaneously creates a static electric charge. Charged particles of dust are attracted to surfaces with the opposite charge. An antistatic spray may help by providing a very thin layer of insulation between the opposite charges.