A 16-min time series of two-dimensional "Multichanel Subtractive Double Pass" spectrograms, recorded in the NaD_2_ 5690 line, has been used to study the vertical structure of the photosphere and, in particular, the penetration of granules. A statistical and a morphological investigations have been made. The 5-min oscillations have been carefully filtered in the k-ω space. Intensity fluctuations associated to granules disappear in a very short distance, about 60 to 90km above the continuum level. The intensity features in the upper photosphere are not related to the granules. The velocity fluctuations associated to the granulation, cross the whole thickness of the photosphere. The photosphere can thus be separated into two distinct layers, but only for the intensity features, not for the velocity features which are the same from the bottom to the top of the stable atmosphere. In the lower photosphere, below 90km, only granules are detected. In the upper photosphere, our observations suggest that the weak pattern visible there, is turbulent in origin. In addition to this weak pattern, bright sinking plumes have been discovered; they are associated with strong downflows, often adjacent to strong upflows. The size of most plumes is 1" to 2"; however the most outstanding of them may be as large as 4". Their origin, which may be photospheric or chromospheric, is still unknown.