What two factors determine the attenuation from rain?

The correct choice highlights that attenuation from rain is influenced by radiation wavelength and precipitation strength, both of which play crucial roles in determining how much radar signal is weakened as it travels through rain.

Radiation wavelength is significant because different wavelengths interact differently with water droplets. Shorter wavelengths (like those used in some Doppler radars) are generally more susceptible to attenuation than longer wavelengths. This means that a radar operating at a shorter wavelength may experience greater signal loss due to scattering and absorption when encountering rain.

Precipitation strength, which refers to the intensity of the rainfall, also directly affects attenuation. Heavier rainfall results in more water droplets within the radar beam's path, leading to increased scattering and absorption of the radar signal. The more intense the rain, the greater the impact on the radar signal, thus resulting in higher levels of attenuation.

In combination, these two factors explain why this choice accurately captures the essence of how rain affects radar signals, allowing for a clearer understanding of radar performance in meteorological observations.