an e magazine from ASSAM & NAGALAND      

The emission of 'low energy' solar wind takes place from the so called 'M' regions of the Sun's surface and the 'high energy' from the 'S' regions. M and S regions continuously expand, contract or even interchange with discernible variation of solar activities. The distribution, quantum and speed of emission of low energetic particles from the M regions and high energetic particles from the S regions of the Sun even within the equatorial belt is not uniform.

The Sun itself revolves on its own axis at an uneven speed. The poles take about 30 and the sub-equatorial region roughly the time length of 27 mean terrestrial

days to complete one revolution. If the equatorial and subequatorial zone of the Sun is divided into 27 equal segments, the Earth faces a different segment of the Sun each day. As each solar segment has its own specific quantity and intensity of solar wind emission, the Earth will be facing an energy field of different intensity each new day changing everyday till the 27th day, and then the cycle will begin anew.

The statement made above is oversimplified as a number of rectifications, which have been mentioned earlier, will have to be brought in. One cannot deny the fact that when the Earth will face a 'high energy' solar segment, subsequently it will receive more energy and after the days when the Earth faces a 'low energy' segment of the Sun, subsequently it will receive low solar energy. The results of energy variations will be manifested in the earth's atmosphere 28 to 48 hours afterwards, and can be measured as higher solar particle concentration (density) and greater intensity of solar magnetic variations.

The movement and activities of the solar wind is by far more complex than the activities of the light, where the effect is instantaneous. The flight of the solar wind and the 'energy relationship between the Earth and the 'solar segment' will be modified by the following factors:

(i) All other things being equal due to the rotation of the Sun, the solar wind emanated from the western side of the solar orb will reach the Earth a few hours earlier than the solar wind released from the eastern side.

(ii) The speed of the solar wind in the interplanetary space will depend upon the velocity at which it was initially expelled from the Sun. It may be as low as 306 km per second if emitted during a very tranquil, non flaring period and may be as high as 842 km per second (R.Lust -1967) if spewed out during violent solar storms accompanied by formation coronal flares and resulting sunspots. Therefore depending upon the segment of the Sun (western or eastern), and the prevailing conditions (stormy or tranquil) the solar wind may take 28 to 48 hours to reach the Earth.

It will appear that if a 'disturbed segment' follows a 'quite segment' the faster particles of the disturbed segments will overtake the end fraction of slower particles originated in the quieter segment and the energy field effects with Earth's atmosphere will get smudged.

(iii) End of one cycle and beginning a new cycle is accompanied by reversal of polarity, but that does not mean reversal of polarity does not take place within one 27-day cycle.

Even after so many modifying factors effecting the nature and flow of the solar emanation, the correlation between the sequence or periodicity of high and low energy segments of the Sun facing the Earth and the sequence of terrestrial days showing energy levels reflecting the solar energy levels will be maintained. That is, if on the solar disk, one high energy emitting segment is followed by two consecutive low energy segments, succeeded by again one high energy segment, then on the Earth's atmosphere, where the solar- terrestrial magnetic intensity is measured, it will be found that one high energy day will be followed by two days of comparatively low energy level and the fourth day again will show rise of surfacial electromagnetic energy level. This similarity of sequential pattern is not synchronous, the earthly series will be delayed by about two days and on the fourth day there will be smudging effect to a large extent as faster energetic particles will partially overtake the older and slower rays and particles emitted on the third day. It can be easily established that enhanced beam of solar particles are the primary causes of geomagnetic disturbances (T. Obayashi -Solar wind geomagnetic field interaction disturbed. Solar -Terrestrial Physics. edit. J. W. King and W.S. Newman -1967. Academic Press. London). It has been established that a visible intense solar flare, is followed by increase of geomagnetic disturbances on the Earth's atmosphere which are measurable with the instruments placed on orbiting satellites, and to a lesser extent by the ground stations. Sometimes geomagnetic disturbances may increase even without visible solar flares, but other factors will indicate enhanced solar activities. The time gap between the visible flare and increased disturbances is 30-40 hrs.

The protons form the major constituent material of the solar wind, and the enhancement in the beam of solar particles will be reflected in increase of density (number of protons). It may rise from 0.01 protons to 80 protons per cubic centimeter as the energy field changes from the quiet to a disturbed condition. In the 27-day solar- terrestrial energy cycle, which is our object of study, distinct relationship between the solar activities and speed, and density of protons can be established.

About the 27-day cycle P. Seymour has written (Cosmic Magnetism-1986. P. 40). "There is also a broad line near 27-day, which may be due to some effect connected with the rotation of the Sun on its axis."

The present author will strive to demonstrate that the periodicity of high and low of solar radiation, high and low of magnetic disturbances on the Earth's atmosphere, and high and low of concentration of low energy protons in the Earth's atmosphere all the three will follow exactly the same sequential pattern, thereby ruling out any "connection with the lunar month" and should confirm "effects connected with the rotation of the Sun on its axis."

That the solar -terrestrial magnetic disturbances are linked to solar energy emission level, and that their sequential of T. Obayashi (1967 opp. Cit.). "A major peak of geomagnetic activity SKp extends from 5 to 10th day followed by a decrease in cosmic-ray intensity. Minor peaks appear during 15th to 25th day (P. 115. Opp.cit). This statement was made in reference to 27-day recurrence patterns of geomagnetic activities and cosmic ray intensity. The 27-day periodic variation is best reflected by variations of concentration of low -energy solar proton (MeV range) is confirmed by a number of other authors (R. Lust -The properties of interplanetary Space. P.37). Most convenient unit to monitor the variations of solar flux intensity is density, as fluctuation in density will be observed even without any visible solar flare.