This data set contains information about the sky and weather conditions in Albuquerque, NM and Eugene, OR. For each site, the data is minutely for the period of two years. The data includes hemispherical images of the sky, measurements of the hemispherical (global) irradiance in an arc swept from east to west, and relevant weather data (primarily irradiance) from on site weather stations. This data was collected as part of a project for single-axis solar trackers. This submission also includes a report which provides more context and details to the data set. The authors recommend reading the SAND report (see the "Project Report" resource below) before inspecting the data.