Minimal impact of condensation nuclei characteristics on observable Mesospheric ice properties

Noctilucent clouds and polar mesospheric summer echoes are both manifestations of ice particles near the summer polar mesopause. These ice particles are believed to form mainly on pre-existing ice condensation nuclei. The characteristics and especially the concentrations of such nuclei have been considered important factors in determining ice properties. More ice condensation nuclei would, given the limited amount of water vapor, yield more but smaller ice particles, and thus a dimmer noctilucent cloud. However, here it is shown that the sensitivity of observable ice properties to condensation nuclei concentration is much less than one would expect from the simple situation described above. In particular, both ice mass and cloud brightness is close to independent of condensation nuclei concentration. The reason for this lack of sensitivity is further examined.