Light Detection and Ranging (LIDAR) is an active remote sensing technique analogous to the Radio Detection and Ranging (RADAR) in the sense that they both operate on the same principles, but LIDAR employs a laser beam instead of radio waves.
Sunphotometry is a passive remote sensing technique used to measure the intensity of the sunlight through the atmosphere. Such measurements, made in several narrow bands of the solar spectrum, provide information on the properties of aerosols and important trace gases that can be used in climate modeling and air pollution monitoring