The cloud drop effective radius (alternatively cloud effective radius or simply effective radius when in context) is a

weighted mean The weighted arithmetic mean is similar to an ordinary arithmetic mean (the most common type of average), except that instead of each of the data points contributing equally to the final average, some data points contribute more than others. The ...

of the size distribution of cloud droplets. The term was defined in 1974 by

James E. Hansen James Edward Hansen (born March 29, 1942) is an American adjunct professor directing the Program on Climate Science, Awareness and Solutions of the The Earth Institute, Earth Institute at Columbia University. He is best known for his research ...

and

Larry Travis Larry E. Travis (June 5, 1929 – August 14, 2017) was a Professor Emeritus at the Department of Computer Sciences as the University of Wisconsin–Madison. He had a faculty position at the University of Wisconsin as early as 1964 (two years befor ...

as the ratio of the third to the second moment of a droplet size distribution to aid in the

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of remotely sensed data. Physically, it is an area weighted radius of the cloud drop particles. Mathematically, this can be expressed as :

r_e = \dfrac

. The global effective particle radius has different values for water and ice clouds: the former is around 14 μm, whereas for ice it is around 25 μm. Studies also indicate that the effective cloud droplet radius is larger over oceans than over ground by 15%-20%. By contrast, the difference in the ice particle size over land and oceans is much smaller (only 5%).

References

Atmospheric sciences Atmospheric radiation Cloud and fog physics {{scattering-stub fr:Physique des nuages#Distribution des gouttes

See also

References