Articles | Volume 12, issue 2
Atmos. Meas. Tech., 12, 1295–1309, 2019
Atmos. Meas. Tech., 12, 1295–1309, 2019

Research article 28 Feb 2019

Research article | 28 Feb 2019

Halo ratio from ground-based all-sky imaging

Paolo Dandini et al.

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Cited articles

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Short summary
The halo ratio indicates the strength of the 22° cirrus halo and gives valuable information on cloud properties. We obtain it from all-sky images by applying a range of transformations and corrections and averaging brightness azimuthally over sun-centred images. The ratio is then taken at two angles from the sun, 20° and 23°, in variance from previous suggestions. While we find ratios > 1 to be linked to halos, they can also occur under scattered cumuli as artefacts due to cloud edges.