Note: Active optical detection of cloud from a balloon platform

Harrison, R. G. ORCID: https://orcid.org/0000-0003-0693-347X and Nicoll, K. A. ORCID: https://orcid.org/0000-0001-5580-6325 (2014) Note: Active optical detection of cloud from a balloon platform. Review of Scientific Instruments, 85 (6). 066104. ISSN 0034-6748 doi: 10.1063/1.4882318

Abstract/Summary

A disposable backscatter instrument is described for optical detection of cloud in the atmosphere from a balloon-carried platform. It uses an ultra-bright light emitting diode (LED) illumination source with a photodiode detector. Scattering of the LED light by cloud droplets generates a small optical signal which is separated from background light fluctuations using a lock-in technique. The signal to noise obtained permits cloud detection using the scattered LED light, even in daytime. The response is interpreted in terms of the equivalent visual range within the cloud. The device is lightweight (150 g) and low power (∼30 mA), for use alongside a conventional meteorological radiosonde.