We have found that in the absence of self-focusing, induced absorption of a pulsed Ti:Sa-laser radiation of femtosecond duration by atmospheric air and water vapor increases proportionally to the laser pulse energy E. In the case of Gaussian beams of 2.5-mm radius, the coefficient of induced absorption by air at atmospheric pressure changes with the pulse energy at a rate of dk/dE = (2,48 ± 0,45) • 10-7 см-1 • mJ-1 (pulse duration of 190 fs), and that of water vapor at the pressure of 13 mbar at a rate of dk/dE = (1,54 ± 0,20) • 10-8 см-1 • mJ-1 (pulse duration of 120 fs). The absorption coefficient of air measured at E ≈ 0, linear absorption coefficient, using a femtosecond pulse well agrees with the coefficient of radiation absorption by water vapor in the atmospheric air calculated using HITRAN database.