Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

What convention is used for the illumination and view angles?

Zenith angles are positive values measured from the local vertical at each point. Azimuth angles are measured clockwise from the direction of travel to local north. For both the Sun and cameras, azimuth describes the direction in which the photons are traveling. According to this convention the solar azimuth angle is therefore near 270 degrees when Terra is close to the equator, because of its morning equator crossing time. Additionally, the difference in view and solar azimuth angle will be near 0 degrees for forward scattered light, and near 180 degrees for backward scattered light. Sun and View angles are available in the MISR Geometric Parameters (MIB2GEOP) data product. Sun angles are also available in the L1B2 data files.