The SPHERE project studies primary cosmic rays by registration of the extensive air showers (EAS) Cherenkov light reflected from the snow covered ground. The SPHERE project is the first successful implementation of this new EAS detection method, first proposed by Alexander Chudakov and first implemented by Rem Antonov. The SPHERE-2 experiment was designed for studies in the 10--1000 PeV energy range. The detector was lifted by a balloon to altitudes of up to 900 m above the snow covered surface of Lake Baikal. Measurements were performed in 2011--2013.

Here we present an overview of the SPHERE-2 detector telemetry monitoring systems along with the analysis of the measurements conditions including atmosphere profile. The analysis of the detector state and environment atmosphere conditions monitoring provided various cross-checks of the detector calibration, positioning, and performance.