The Significance and Measurement of Ice Nucleating Particles (INPs) in the Atmosphere

Airborne particles (Aerosols) which are able to catalyze the formation of ice from supercooled water droplets in our atmosphere exert a disproportionate impact on cloud properties. Aerosol particles thought to be of importance in making ice nucleating particles (INPs) process include mineral dusts, soots, volcanic ashes, along with biogenic materials such as fragments of pollen, bacteria and fungi. However, the relative importance of these different classes of aerosols to facilitate the formation of ice in clouds remains highly uncertain. A significant factor in our current lack of understanding results from the disparate methods with which researchers have quantified the ice nucleating abilities of these aerosols. We apply a new experimental technique in which droplets of microliter volume containing ice-nucleating material are cooled down at a controlled rate and their freezing temperatures recorded. Valuable data has already been obtained. The result shows that when the temperature decreases the concentrations of INPs increases and meteorological conditions such as wind speed, temperature and relative humidity as well as the trajectories of the air masses affected the INPs concentrations. Higher concentrations were observed on days when the winds were stronger.