DECAY OF A VERTICAL PLASMA-COLUMN - A MODEL TO EXPLAIN VLF SPRITES

VLF sprites are identified by high angle scattering of VLF transmissio ns by the conducting plasma columns which appear as the luminous colum ns of ''red sprites''. VLF sprites are ''early/fast Trimpis'' and prob ably vice versa. Recently discovered properties of early/fast Trimpis are the logarithmic decay of the amplitude of the scattered signal and monotonic variation of its phase. These properties are explained in t erms of scattering from a vertical column or set of columns extending from 50 km (or lower) altitude to about 80 km.