Vaisala CT25K - 1. General Information; 1.1 Product Overview

Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
1
1. GENERAL INFORMATION
1.1 Product Overview
Ceilometer CT25K measures cloud heights and vertical visibilities. The small
and lightweight measurement unit suits well for mobile operation.
The CT25K Ceilometer employs pulsed diode laser LIDAR technology
(LIDAR = Light detection and ranging), where short, powerful laser pulses
are sent out in a vertical or near-vertical direction. The reflection of light -
backscatter - caused by haze, fog, mist, virga, precipitation and clouds is
measured as the laser pulses traverse the sky. The resulting backscatter
profile, i.e. signal strength versus height, is stored and processed and the
cloud bases are detected. Knowing the speed of light, the time delay between
the launch of the laser pulse and the detection of the backscatter signal
indicates the cloud base height.
The CT25K is able to detect three cloud layers simultaneously. Besides cloud
layers it detects whether there is precipitation or other obstructions to vision.
No adjustments in the field are needed. The embedded software includes
several service and maintenance functions and gives continuous status
information from internal monitoring. The software is designed to give the
full backscatter profile.
MEASUREMENT UNIT
SHIELD
PEDESTAL
9412-026
Figure 1-1 Ceilometer CT25K