Observations of NO2 from the limb infrared monitor of the stratosphere (LIMS) experiment in high-latitude summer are presented. Appropriate selection of latitude and days during the month of May yields NO2 observations obtained during the afternoon and evening at solar zenith angles from about 35¿ to 110¿. These data show that the NO2 abundances in stratosphere become strongly dependent on the solar zenith angle for angles exceeding about 80¿. Model calculations and other observations suggest that from about 80¿ to 95¿ this dependence probably reflects variations in the propagation of the visible radiation that photodissociates NO2. The data obtained at zenith angles greater than about 905¿ provide clear evidence for the night decay of NO2 to form N2O5, and the observed decay rate is shown to be consistent with present theory.