  We present a theoretical estimate of the atmospheric Newtonian noise due to
fluctuations of atmospheric mass densities generated by acoustic and turbulent
phenomena and we determine the relevance of such noise in the
laser-interferometric detection of gravitational waves. First, we consider the
gravitational coupling of interferometer test-masses to fluctuations of
atmospheric density due to the propagation of sound waves in a semispace
occupied by an ideal fluid delimited by an infinitely rigid plane. We present
an analytical expression of the spectrum of acceleration fluctuations of the
test-masses of the interferometer in terms of the experimentally obtainable
spectrum of pressure fluctuations. Second, we consider the gravitational
coupling of interferometer test-masses to fluctuations of atmospheric density
due to the propagation of sound waves generated in a turbulent Lighthill
process. We present an analytical expression - in the Fourier space - of the
spectrum of acceleration fluctuations of the test-masses of the interferometer.
Finally, we discuss the relevance of these noise sources in the detection of
gravitational waves by comparing the estimated spectral densities of Newtonian
atmospheric noises considered here to the expected sensitivity curve of the
VIRGO detector.
