PDF of the normalized mass surface density X_n of cylindrical clouds having a density distribution with n = 1 (gray lines) and n = 4 (black lines). The clouds have an overdensity (1 /q) of either 10 or 100. The long dashed curves show the asymptote for infinite high overdensity. The dotted lines mark the asymptotic value at the poles. The short dashed lines give the asymptotic values in the limit of high and low values of X_n.