Fig 1. Fraction of droplets frozen as a function of temperature for nanolitre and microlitre volume supercooled water droplets containing Soufriere Hills volcanic ash particles.

Droplets with diameters in the range of 30–70 μm (nanolitre volumes) were cooled at 10 K min^-1 and had ash concentrations of 0.1 wt%. The 1 microlitre droplets had an ash concentration of 0.01 wt% and were cooled at rates from 0.2–2 K min^-1.