During the day of September 20, 1982 16 high resolution atmospheric spectra were recorded at regularly spaced time intervals from sunrise to sunset using the Fouriet transform spectrometer of the McMath solar telescope of Kitt Peak National Observatory. Using well isolated NO2 absorption peaks appearing in the 2850-2950 cm-1 region, it has been possible to measure precisely the daytime variation of the NO2 vertical column density. A rapid increase from sunrise to noon is observed followed by a slower increase in the afternoon. A comparison with the predictions of a photochemical model is given.