The physical state of matter at the base of the coronal hole at the level of the chromosphere was studied from observations in the Hα and He I 10830 Å lines. The polar coronal hole was observed in the northern hemisphere in 2015-2017 during 24 Carrington rotations. Boundaries of the coronal hole were determined from observations in the 193 Å line. Intensities in the lines were expressed in units of the unperturbed Sun. For the He I 10830 Å line, the relative intensity of coronal holes varied within 1.0046-1.0355, for the Hα line-within 0.9676-0.9753. Models of the chromosphere explaining the observed features are calculated. Models are built based on calculations of the He I and Hα line profiles in the non-LTE approximation. The difference in the atmospheres of coronal holes and the quiet Sun begins at the level of the upper photosphere at T > 410 3 K. Throughout the chromosphere, the temperature and density in the coronal hole is lower than in the undisturbed chromosphere.
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