Weather radars are used to locate precipitation, calculate the direction of its movement and determine its type (rain, snow, hail, etc.). They are also called meteorological, weather or (rarely) Doppler radars. Modern weather radars can additionally detect the direction of motion of rain droplets, as well as the intensity of the rainfall itself. For more information, please view weather radars on Wikipedia.
Information from weather radars is always delayed. Depending on the type of radar, its creation date and the computing power of the regional center, precipitation maps are available with up to 30 minutes delay. You can view the time of the last radar image by selecting the radar pin on the map (iOS and Android applications only).
Quite often radar gets a bad reflection of signals that leads to interference in the final images. This noise can appear as rays from the image center to its ends (common with Spanish radars), chaotic small “rainfall” areas in the images (common with US radars) or persistent noise in the same place (common in with Canadian and Romanian radars). It sometimes looks like circular interference when either all or part of the image falls into the “precipitation zone” (common with Thai and Serbian radars). RainViewers’s processing software removes most of this noise, but not all, which is why you will sometimes see these “weather anomalies”.