A good rule of thumb is that everything that can interact with electromagnetic (EM) radiation is an antenna, which includes our mostly-salty-water-containing bodies and also raindrops and moisture in the air. This can be both a benefit or a curse, depending on whether you’re trying to broadcast a signal in rainy weather or operating a weather radar. Here it’s essential to understand what kind of antenna a raindrop really is to optimize for either scenario, which is where a video by [Marshall Bruner] provides a solid primer.The video focuses on the Rayleigh regime, which may be familiar from atmospheric Rayleigh scattering that also affects EM radiation in the visible spectrum, giving those of us gifted with retinas capable of color vision those nice blue skies.As the EM radiation passes through these little droplets in the air, their neutral alignment gets disrupted and causes them to turn into dipole antennae, moving along with the incoming frequency. The backscatter part of this event is what returns to the emitter, such as a weather radar. Here the volume and permittivity of the moisture sphere determines the strength of the signal, which is great if you’re actually operating a weather radar and wants to map out the moisture in some clouds, including the presence of snow.There’s quite a lot of mathematics involved which is covered in the video and expanded upon in a related Python notebook.