Laboratory and field measurements of raindrop oscillations

Shape and oscillations of the water drops freely suspended in a horizontal electric field: A wind tunnel study

“…Another feature of our results is the decrease in oscillation amplitude for drops 46 mm diameter in the absence of an electric field. Such a trend is also seen in the data of Tokay et al (2000) for drops 45 mm diameter.…”

“…Our results fall between the values of Szakáll et al (2010) and Tokay et al (2000). Drops in the experiments of Kubesh and Beard (1993) and Andsager et al (1999) are confined to relatively smaller sizes.…”

“…The FFT analysis shows the existence of two peaks in the spectrum for larger drops (d Z5.11 mm). The dominant, highest peak in the spectrum corresponds to fundamental mode of oscillation and its frequency matches well with the frequency calculated by 10 T method Kubesh and Beard (1993), Andsager et al (1999), Tokay et al (2000) and Szakáll et al (2010) are also plotted.…”

“…Vertical bars show standard errors in the amplitude. The experimental data of Kubesh and Beard (1993), Andsager et al (1999), Tokay et al (2000) and Szakáll et al (2010) for the amplitude of oscillations in zero electric fields are also shown in Fig. 6.…”

Toward elucidating the microstructure of warm rainfall: A survey

“…Both field and laboratory observations [e.g., Gunn , 1949; Jones , 1959; Beard et al , 1989a, 1991; Beard and Tokay , 1991; Andsager et al , 1999; Tokay et al , 2000; Thurai and Bringi , 2005] have shown that a particular raindrop size (class III) can have a wide range of instantaneous shapes (hence chord ratio values) because of drop oscillations. Periodic oscillations of raindrops falling at terminal velocity are visualized for the first time by Testik et al [2006] by using high‐speed imaging.…”