Pyrgeometer is designed to measure the atmospherical far infrared radiation. The instrument has a silicon window with solar blind filter on the inside to block all solar radiation. The outside of the window is coated to protect it from environmental influences. A socket is fitted for the signal cable with waterproof plug. An internal temperature sensor is available to calculate the downward Far-InfraRed irradiance. CGR 4 pyrgeometer is an instrument for the highest quality scientific measurements.

The specially designed meniscus dome provides a 180º field of view with negligible directional response error. A hard-carbon coating on the outside of the dome smoothes the spectral response and provides extra protection to the silicon surface. The excellent thermal stability of the dome construction and coupling to the instrument body eliminates the need for dome temperature measurements or dome shading. CGR 4 can be fitted with the CV 2 Ventilation Unit to further improve its performance. A waterproof socket is fitted for the signature yellow signal cable, which is available in a range of lengths pre-wired to the waterproof plug. The integral bubble level is raised to the top of the housing and can be viewed without removing the redesigned snap-on sun shield, which also covers the connector. The connector with gold-plated contacts allows for easy exchange and re-calibration.