Assertion             :       The electrical conductivity of earth?s atmosphere decrease with altitude. Reason                 :       The high energy particles (i.e. g-rays and cosmic rays) coming from outer space and entering our earth?s atmosphere causes ionisation of the atoms of the gases present there and the pressure of gases decreases with increase in altitude. 

            We know, with increase in altitude, the atmospheric pressure decreases. The high energy particles (i.e. g-rays and cosmic rays) coming from outer space and entering out earth?s atmosphere cause ionisation of the atoms of the gases present there. The ionising power of these radiation decreases rapidly as they approach to earth, due to increase in number of collisions with the gas atoms. It is due to this reason the electrical conductivity of earth?s atmosphere increase with altitude.