What is the actual wavelength and velocity of a near-infrared beam ( = 0.899m) of light modulated

What is the actual wavelength and velocity of a near-infrared beam (λ = 0.899μm) of light modulated at a frequency of 330 MHz through an atmosphere with a dry bulb temperature, T, of 24° C, a relative humidity, h, of 69%, and an atmospheric pressure of 933 hPa?