Airborne measurements of cloud and precipitation particles are used to study microphysical processes involved in their formation and evolution.
We utilise a range of instruments flown on board the FAAM BAe146 research aircraft. These include probes able to count and size cloud droplets, raindrops, ice crystals and snowflakes. We also use instrumentation to measure bulk liquid and ice water contents, to sample the physical and chemical characteristics of atmospheric aerosol particles and to measure the dynamical and thermodynamical characteristics of the air.
An important interest is stratocumulus cloud within the atmospheric boundary layer. This is maintained by a near-balance of physical processes including radiation, turbulent transport of heat and moisture and microphysics. The correct representation of interactions between these various processes is very important in forecasting the formation, variability and break-up of stratocumulus. We are currently using field observations to compare with forecasts of the cloud made with the Unified Model.
We also study the formation and evolution of ice within clouds. This can have a significant impact on the evolution of precipitation from cloud systems around the UK. Below 0C, ice can grow more quickly than liquid cloud droplets due to the lower saturation vapour pressure over an ice surface. We are developing an ice nucleus (IN) counter to detect the aerosol particles involved in the initiation of ice in the mid-troposphere.