[1] The rare phenomenon of ultrarelativistic electron precipitation into the middle polar atmosphere, prevalent under calm geophysical conditions, was established from ground-based radio wave measurements during the period of 1982-1992. Precipitating electrons with energy 100 MeV and sufficient density to generate X-and gamma-ray bremsstrahlung create a sporadic layer of ionization in the atmosphere under the regular D layer of the ionosphere. Very low frequency radio waves reflect from this sporadic layer with abnormal weakening and with an unusually low height of reflection. The layer has a horizontal linear scale of about several thousand kilometers, with a thickness in altitude of about 20-30 km, and persists for several hours. Due to this layer of electric conductivity, the effective height of this "ground-ionized atmosphere" waveguide diminishes in exceptional cases by 2-2.5 times. The auroras of X-ray bremsstrahlung have been detected by the reflection of radio waves with wavelengths of 30-20 km. This phenomenon may be termed "a polar cap absorption effect of the second kind" as an electron analog of proton precipitation.Citation: Remenets, G. F., and M. I. Beloglazov (2013), Ultrarelativistic electrons in the near cosmos and X-ray aurora in the middle polar atmosphere,