In fact, the attenuation of rain on EMW(electromagnetic waves) below 10 GHz is relatively slight, but for EMW above 10 GHz, the impact of rain attenuation is very obvious. 

When EMW passes through the rainfall area, the rain not only absorbs the energy of the radio wave, but also scatters it. This absorption and scattering together form electromagnetic wave attenuation. Scattering can also cause large-scale EMW interference and have a depolarization effect on electric waves. These attenuation and interference are called rain attenuation. This attenuation reduces the reliability and performance of the communication link.

Friends who know satellite TV know that heavy rain can cause communication interruption in K-under, and the attenuation caused by K-above is more serious than that in K-under. The magnitude of rain attenuation is related to many factors such as electromagnetic frequency, rainfall rate, size and shape of raindrops, polarization direction of radio waves, location of receiving location and altitude.

However, for the shortwave, VHF/UHF band, which amateur radio enthusiasts usually use, the effect is generally not significant. Therefore, rainfall has little effect on HF propagation, and the same is true for amateur satellite communications in the VHF/UHF band.