When you think of precipitation, you may think of heavy rain during the rainy season or summer. In mid-latitudes, even if the water particles (hydrometeors) that fall on the ground are liquid, they often exist in a solid state, or ice, because the temperature high in the atmosphere can be well below 0 degrees Celsius.

Compared to clouds that occur at temperatures above 0 °C, many physical processes must be taken into account.  The shapes, densities, and sizes of these ice particles vary; supercooled liquid at temperatures exist down to -38 °C; liquid and solid particles interact each other; electric charges cloud/precipitation particles separate within clouds.  Snowfall forecast can be a difficult task due to these reasons.

Our laboratory aims to understand the precipitation phenomena and identify the underlying factors to improve weather predictions by combining observational data and numerical models.

Have you imagined how rain drops form in the atmosphere?  The science of cloud and precipitation was stimulated by our needs for water during dry seasons, and weather modification technology has been developed based on the science.  Under climate changes, precipitation distribution, strength and the type (rain or snow) are expected to change.  Understanding growth process from aerosol particles to rain drops/snow is important to improve climate and weather prediction.

Fundamental processes include nucleation, cloud particle activation, vapor deposition/condensation, collision-coalescence-breakup, and melting processes.  The flow fields around the particles as well as the physical characteristics of the particles determine the growth rates.  We are interested in particle-scale phenomena to quantify the growth based on numerical approach.