At any given time, clouds cover approximately 60% of the Earth’s surface and they strongly influence weather and climate; however, they are one of the largest sources of uncertainty in climate models and predictions of atmospheric effects on remote sensing measurements. Knowing the cloud thermodynamic phase – whether a cloud is composed of ice crystals or liquid particles – is critical in these applications. Knobelspiesse et al. (Atmos. Meas. Tech., 8, 1537–1554, 2015) showed theoretically that the sign of the S1 Stokes parameter can be used to detect cloud thermodynamic phase when observed with a ground-based passive polarimeter and demonstrated this principle with a zenith-viewing polarimeter. In this theory, a positive S1 value indicates a liquid cloud, while a negative S1 value indicates an ice cloud. In this paper, we report the use of our all-sky polarimeter, operating at 450 nm (10 nm band) to detect ice, liquid, and multi-layered clouds. The cloud thermodynamic phase was independently verified with a dual-polarization lidar pointed at the zenith.