The Cloud, Aerosol, and Precipitation Spectrometer (CAPS) is designed to measure size distributions of airborne particles. It contains the Cloud Imaging Probe (CIP) that measures the sizes of larger particles within the range between 12.5 μm and 1.55 mm with a shadow detector; Cloud and Aerosol Spectrometer (CAS) that measures the size of smaller particles between 0.51 and 50 μm; and Hotwire Liquid Water Content Sensor (Hotwire LWC) that estimates liquid water content using a heated sensing coil and measuring the power necessary to maintain the temperature. Additional measurements include airspeed using a differential pressure measurement through a pitot tube, temperature and relative humidity. It is primarily an aircraft mounted instrument, although CAS has been used in the past during ground based deployments.