Ice in clouds experiment—layer clouds. Part I: Ice growth rates derived from lenticular wave cloud penetrations

Data are acquired from 139 liquid cloud penetrations flown approximately along or against the wind direction. A mean linear ice growth rate of about 1.4 μm s⁻¹, relatively independent of particle size (in the range 100--400 μm) and temperature is deduced.

Using the particle size distributions measured along the wind direction, the rate of increase in the ice water content (IWC) is calculated from the measured particle size distributions using theory and from those distributions by assuming different ice particle densities; the IWC is too small to be measured. Very low ice effective densities, <0.1 g cm⁻³, are needed to account for the observed rate of increase in the IWC and the unexpectedly high linear growth rate.