The Vaisala Ceilometer CL31 is a compact and lightweight instrument for the measurement of cloud base height and vertical visibility. It is able to detect up to three cloud layers simultaneously.
The CL31 employs pulse diode laser (LIDAR) technology. Measurement range is from zero to 25,000 feet. The CL31 uses second-generation enhanced single lens technology, which provides reliability during precipitation, low clouds and ground based obstructions, which are the most critical phenomena in aviation safety.
A powerful Digital Signal Processor enables a fast measurement cycle. The minimum cycle for the CL31 is two seconds, compared to the 15-30-second cycle of current ceilometers. One of the benefits of fast measurement is the improved detection of thin cloud patches below a solid cloud base. The reporting interval can be adjusted between two and 120 seconds, providing flexibility for different applications. The CL31 also provides a full backscatter profile for data visualization and research purposes.
The unit is fully automatic and has extensive self-diagnostics with fault analysis.