It is pointed out, that raindrop size distributions widely used to estimate theoretically the radio waves specific attenuation due to rain in the microwave range, inadequately represent the quantity of small raindrops. According to experimental data for some geographical regions (for example, Japan) the quantity of these raindrops is too large. This fact restricts the use of well known distributions in the terahertz range. So, taking into account small raindrops, the new distribution is

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... and the radio waves specific attenuation due to rain is estimated more precisely for mentioned and some other geographical regions.