When an RF lightning signal is detected at a single location, one can determine its direction using a but it is difficult to determine its distance. Attempts have been made using the amplitude of the signal but this does not work very well because lightning signals greatly vary in their intensity. Thus, using amplitude for distance estimation, a strong flash may appear to be nearby and a weaker signal from the same flash – or from a weaker flash from the same storm cell – appears to be farther away. One can tell where lightning will strike within a mile radius by measuring ionization in the air to improve the accuracy of the prediction.